E4
8
SCIENCE
FIRST QUARTER
LEARNING ACTIVITY SHEET
Republic of the Philippines
Department of Education
COPYRIGHT PAGE
Learning Activity Sheet in SCIENCE
(Grade 8)
Copyright © 2020
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Table of Contents
Page
number
Competency
Investigate the relationship between the
amount of force applied and the mass of the
object to the amount of change in the object’s
motion
Infer that when a body exerts a force on
another, an equal amount of force is exerted
back on it
Identify and explain the factors that affect
potential and kinetic energy
Investigates the effect of temperature to the
speed of sound
Explain the hierarchy of colors in relation to the
energy of visible light
Differentiate between heat and temperature at
the molecular level
Infer the relationship between current and
voltage
Explain the advantages and disadvantages of
series and parallel connections in homes
Explain the functions of circuit breakers, fuses,
earthing, double insulation, and other safety
devices in the home
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SCIENCE 8
Name of Learner:
Grade Level:
Section:
Date:
LEARNING ACTIVITY SHEET
Force and Motion
Background Information for the Learners:
In your Grade 7, you described the motion of objects in terms of distance,
displacement, speed, velocity, and acceleration. As you remember, distance is the total
length of path travelled. Displacement on the other hand is the shortest distance the object
makes with respect to the reference point. In other words, distance is measured by virtue of
the object’s path, while displacement is measured by virtue of the object’s final position with
the point of reference.
The time rate at which an object changes distance is speed. Speed tells us how fast the
object is going. When the speed of the object is zero, it means that the object is at rest. When
the speed of an object has a magnitude equal to any number, it means that the object is
moving.
The time rate of change in displacement is velocity. Velocity describes how fast the
object changes position with respect to the reference point. Zero velocity may mean two
things. It may be that the object is at rest or it is moving but is located just right where the
reference point is at that instant of time! Just like when you are running around the oval or
making a U-turn and returned to the spot where you started.
Objects do not usually travel in uniform speed or uniform velocity. This means,
velocity changes over time. Objects usually speed up or slow down. Acceleration tells how
fast an object changes its velocity.
When the acceleration of the object is zero, it means that the object is in equilibrium
condition or a state of balance. In other words, the object may not be moving (static
equilibrium), or the object is moving at constant velocity (dynamic equilibrium). When this
equilibrium condition is disturbed, the object’s state motion is also disrupted. An object that
is initially at rest may now begin to move. Similarly, an object that is initially moving at
constant speed or constant velocity may speed up, may slow down, or may change direction.
In other words, the object accelerates.
What causes these changes in an object’s motion and how does it affect acceleration?
These are the things that we will investigate through this learning activity sheets.
1
Learning Competency with Code:
Investigate the relationship between the amount of force applied and the mass of the object to
the amount of change in the object’s motion. (Quarter 1, Week 1, S8FE-Ia-15)
Activity 1. Loop-a-Word
Directions: There are 15 words related to motion which are hidden in the box below. Locate
and encircle them.
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2
Activity 2. What can Force Do?
Directions: Have you experienced playing football or have you ever watched a football
game? Study the picture below and answer the questions that follow.
1. In a football game, what is exerted on the ball as the player kicks it?
2. If the football is initially at rest, what happens to its speed as the player kicks it?
3. While the football is rolling on the ground, does the surface of the ground offer an
opposite force on the ball?
4. What is this force exerted by the ground surface on the ball?
5. What is the effect of this force to the football’s speed?
6. How about when another player blocks a flying football. Does the player exert a force
on the ball?
7. What is the effect of this blocking force to the football’s speed?
8. What is the effect of this force to the football’s direction of travel?
Activity 3. Complete the Message
Directions: Fill in the spaces to complete all the statements inside the box. Each space
corresponds to a letter.
Force is any
that causes change in an object’s motion. It
is caused by either
or
. Force is a vector quantity with three
characteristics. These are line of action, , and
.
The SI unit of force is the
. It is denoted in symbol by capital
letter . It is defined as the amount of force that causes a one-kilogram mass object an
acceleration of one meter per second squared in the direction of the force. The expanded
form of this unit is ▪ / 2.
3
Activity 4. Balanced Force
Normally, there are more than one forces acting on an object. When two or more
forces act on an object, they add up algebraically to get the combined effect of the forces
called Resultant Force or Net Force.
Directions: A free-body diagram (FBD) illustrates the forces acting on an object to
determine the resultant force. Interpret the free-body diagrams below and answer the
questions that follow.
A. Tension
A pendulum is suspended at a certain height. The string exerts tension on the bob with
a force of 0.01 N. The weight of the bob is also 0.01 N.
String
Tension = 0.01 N
Pendulum bob
Weight = 0.01 N
1. What are the two forces acting on the bob?
2. What is the direction of each force?
3. Using the Cartesian coordinate plane (x-y coordinate plane) what is the sign of an
upward force?
4. Using the Cartesian coordinate plane (x-y coordinate plane) what is the sign of a
downward force?
5. With positive and negative signs affixed with the upward and downward forces,
respectively, add the two forces together. F net = F1 + F2
6.
7.
8.
9.
10.
If the Fnet on the pendulum is equal to zero, will the bob swing sideways?
If the Fnet on the pendulum is equal to zero, will the bob move upward?
If the Fnet on the pendulum is equal to zero, will the bob move downward?
Are the two forces acting on the pendulum balanced?
What is the Fnet when forces are balanced?
4
B. Normal
A box weighing 20 N is placed on top of a table. The table supports the weight of the
box with an upward normal force of 20 N.
Box
Normal = 20 N
Table
Weight = 20 N
1.
2.
3.
4.
5.
What are the two forces acting on the box?
What is the direction of each force?
Which force takes a positive sign?
Which force takes a negative sign?
With positive and negative signs affixed with the upward and downward forces,
respectively, add the two forces together. F net = F1 + F2
6. If the Fnet is equal to zero, will the box slide sideways?
7. Are the two forces acting on the box balanced?
8. What makes the forces balanced? Describe their magnitude and direction.
C. Friction
A load is pushed to the right along a horizontal floor with a force of 50 N. Static
friction acts towards the opposite direction with a frictional force of 50 N.
Load
Static Friction = 50 N
F1= 50 N
Floor
1. What is the net force or resultant force, Fnet?
2. Are the two forces acting on the load balanced?
3. Will the box move because of balanced forces?
Balanced forces on objects that are initially at rest illustrate the first fragment of
Newton’s First Law of Motion or the Law of Inertia. Complete the statement of the Law of
Inertia for objects that are initially at rest. Write the correct group of words on the blank..
When forces are balanced, objects at rest will
5
.
Activity5. Unbalanced Force
Directions: Read and analyze the given situations and the free-body diagrams below.
Answer the questions that follow.
A. A load initially at rest is pushed to the right along a horizontal floor with a force of
50 N. Starting friction acts towards the opposite direction with a frictional force of 20 N.
Load
Starting Friction = 20 N
F1= 50 N
Floor
1.
2.
3.
4.
5.
What is the magnitude of the resultant force or Fnet?
What is the direction of the net force?
Are the forces balanced?
Will the load move?
In what direction will the load move?
B. A boy pushes a toy car at the back with a force of 2 N, to the right. Another boy
applies a force of 3 N to the right by pulling a string attached in front of the toy. The sliding
friction is 2 N to the left.
Toy car
F1 = 2 N
Friction = 2N
F2 = 3 N
Floor
1. What is the magnitude of the resultant or net force?
2. What is the direction of the resultant force?
3. Will the toy car move? In what direction will it go?
6
C. A ball rolling along a horizontal floor in a straight line path with a constant
velocity of 2 m/s is kicked with a force of 5 N to the right. Rolling friction between the
surfaces of the ball and the ground is 2.5 N
Ball
F1 = 5 N
Floor
Friction = 2N
1.
2.
3.
4.
What is the magnitude of the net, resultant force?
What is the direction of the net, resultant force?
What is the velocity of the ball before it was kicked?
What is constant velocity? Does it speed up, slow down, or remain the same?
5. What is expected to happen to the speed of the ball after the kick?
6. What causes any change in the state of motion of the ball?
Complete the statement of Newton’s First Law of Motion or the Law of Inertia.
Objects at rest will remain at rest. Objects in motion will continue to
in a
line path with a
speed, unless acted upon by
a net force or
force.
7
Activity 6. Effect of Force to Acceleration
Directions: Investigate how different amounts of force affect the object’s acceleration
differently by examining the given situations below. Answer the questions that follow.
A. Two wooden carts below having the same mass of 2 kilograms are lying on a
frictionless horizontal floor. The first cart is pushed with a force of 2 N to the right,
while the second cart is pushed with a force of 4 N to the right.
Cart 1
Fnet = 2 N
Frictionless Floor
Cart 2
Fnet = 4 N
Frictionless Floor
1.
2.
3.
4.
5.
What is the effect of Fnet on both carts?
Which of the two carts will gain greater velocity?
Which of the two carts will accelerate faster?
How many times faster will one cart accelerate compared to the other?
What happens to the acceleration of the cart when the force applied to it is doubled?
B. Another cart is now placed on the same floor. Cart 3 has the same mass of 2
kilograms with Cart 1 and Cart 2. A force of 8 N to the right is exerted to it.
Compare the effect of this force with the first two carts. Answer the questions that
follow.
Cart 3
Fnet = 8 N
Frictionless Floor
1.
2.
3.
4.
5.
6.
How much greater is the net force on cart 3 compared to cart 1?
How much faster will cart 3 accelerate, compared to cart 1?
How much greater is the net force of cart 3 compared to cart 2?
How much faster will cart 3 accelerate, compared to cart 2?
When net force is increased, what happens to the acceleration?
What is the relationship of net force and acceleration?
8
At this point you should be able to state the effect of net force to the acceleration of an
object. This is the first fragment of the statement of Newton’s Second Law of Motion or the
Law of Acceleration!
Encircle the correct term enclosed in the parenthesis to complete each statement in the
box below.
Acceleration is (directly, inversely) proportional to net force. This means that increasing the
net external force applied to an object will (decrease, increase) the object’s acceleration.
When force is doubled, acceleration is (doubled, halved).When force is decreased four
times, acceleration (increases four times, decreases four times).
9
Activity 7. Effect of Mass to Acceleration
Directions: Investigate the effect of mass to an object’s acceleration by examining the given
situations below. Answer the questions that follow.
A. Two wooden carts lying on a frictionless horizontal floor are pushed with equal
amount of force of 10 N to the right. The first cart has a mass of 5 kg, while the
second cart has a mass of 10 kg.
Cart 1
mass = 5 kg
Fnet = 10 N
Frictionless Floor
Cart 2
mass = 10 kg
Fnet = 10 N
Frictionless Floor
1. Which of the two carts will gain greater acceleration?
2. How many times the acceleration of one cart as compared to the other cart be?
3. What affects the difference in the acceleration of the two carts?
4. What happens to the acceleration of the cart when the mass is doubled?
10
B. Another cart is placed on the same floor as shown below. The same amount of force
as Cart 1 and Cart 2 is applied to Cart 3. The mass of Cart 3 is 20 kilograms.
Compare the effect of this mass to acceleration with the other carts. Answer the
questions that follow.
Cart 3
mass = 20 kg
Fnet = 10 N
Frictionless Floor
1.
2.
3.
4.
5.
How much greater is the mass of cart 3 as compared to cart 1?
How much slower will cart 3 accelerate as compared to cart 1?
How much greater is the mass of cart 3 as compared to cart 2?
How much slower will cart 3 accelerate as compared to cart 2?
When the mass of the object is increased, what happens to its acceleration?
At this point you should be able to state the effect of mass to the acceleration of an
object. This is the second fragment of the statement of Newton’s Second Law of Motion or
the Law of Acceleration!
Encircle the correct term enclosed in the parenthesis to complete each statement in the
box below.
Acceleration is (directly, inversely) proportional to mass. This means that increasing the
mass of an object will (decrease, increase) the object’s acceleration. When mass is
doubled, acceleration is (doubled, halved). When mass is decreased four times,
acceleration (increases four times, decreases four times).
11
Activity 8. Applying Newton’s Second Law of Motion
Newton’s second law of motion or the Law of Acceleration can be summarized by
the equation:
Where:
is the acceleration of the object in m/s2;
is the net external force in newtons
(N) ; and, m is the mass of the object in kilograms (kg).
Directions: Apply this formula in solving the following problems. Show your complete
solution.
1. A 5 kg object is pushed along a frictionless floor with a force of 3 N. What is the
acceleration of the object?
2. How much force is needed to cause a 2 kilogram object with an acceleration of 6
m/s2?
3. What is the mass of an object accelerated at 4 m/s2 by a force of 20 N?
4. A cart with a mass of 8 kilograms is pulled along a horizontal rough surface with a
force of 56 N. The floor offers a rolling friction of 16 N on the wheels of the cart.
What is the acceleration of the cart?
Cart
mass = 8 kg
F1 = 56 N
Rough Surface
Rolling Friction = 16 N
12
Activity 9. Summing it Up!
Directions: With activities 1 to 8, you were able to investigate the relationship between the
amount of force applied and the mass of the object to the amount of change in the object’s
motion. In other words you described the motion of an object in terms of the factors causing
such change in motion.
To help you generalize your lesson, answer briefly the questions that follow.
1. In terms of motion, what can net external force do to an object?
2. How does net external force affect the object’s acceleration?
3. How does the object’s mass affect its acceleration?
Reflection:
1. I learned that
2. I enjoyed most on
3. I want to learn more on
13
References:
Campo, Pia C., et. al. 2003..Science – Grade 8. Learner’s Module. Pasig City. Department of
Education. Cordero-Navaza, Delia & Bienvenido J. Valdes. 1996. You and the Natural World Series:
Physics. Quezon City, Philippines. Phoenix Publishing House Inc.,
Padua, Alicia L., et.al. 2003. Practical and Explorational Physics, Modular Approach.
Quezon City, Philippines. Vibal Publishing House, Inc.,
Salmorin, Lolita M. & Alberto V. Florido Jr. 2009. Science and Technology IV-Physics.
Quezon City, Philippines. Abiva Publishing House Inc.,
Silverio, Angelina A. & Rosemarie S. Cabauatan. 2006. Exploring Life Through Science.
Physics. Teachers Guide. Quezon City, Philippines. Phoenix Publishing House, Inc.,
Young & Freedman. 2004. Sear’s and Zemansky’s University Physics with Modern
Physics.11th Edition. San Francisco, California, USA. Pearson Education Inc.,
14
Answer Key
Activity 1.
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Activity 2.
1.
2.
3.
4.
5.
6.
7.
8.
Force
Speeds up or increases
Yes
Friction
It slows down the ball.
Yes
The ball may stop or bounce with a faster / slower speed (answers may vary)
The ball changes direction
15
Activity 3.
Force is any INTERACTION that causes change in an object’s motion. It is caused by
either PUSHor PULL Force is a vector quantity with three characteristics. These are line of
action, MAGNITUDE and DIRECTION.
The SI unit of force is the NEWTON. It is denoted in symbol by capital letter N. It is
defined as the amount of force that causes a one-kilogram mass object an acceleration of one
meter per second squared in the direction of the force. The expanded form of this unit is
kg▪m/s2.
Activity 4.
A. Tension
1. Weight and Tension
2. Upward for tension, downward for weight
3. Positive
4. Negative
5. F net = F1 + F2= 0 Newton
6. No
7. No
8. No
9. Yes
10. Fnet= 0 N
B. Normal
1.
2.
3.
4.
5.
6.
7.
8.
Normal and Weight
Upward for normal, downward for weight
Normal
Weight
F net = F1 + F2= 0 N
No
Yes
Forces are balanced when their F net is zero. Two forces are balanced when they are
equal in magnitude but opposite in direction (* Teacher must emphasize that the
forces must act on the same object)
C. Friction
1. Fnet = 0
2. Yes
3. No
16
Complete the statement below.
When forces are balanced, objects at rest will remain at rest.
Activity 5.
A.
1.
2.
3.
4.
5.
Fnet = 30 N
To the right
No
Yes
To the right
B.
1. 3 N
2. To the right
3. Yes.To the right
C.
1.
2.
3.
4.
5.
6.
3N
To the right
Constant 2 m/s
Velocity/ speed remains the same
The ball will gain speed
Unbalanced force or net force
Objects at rest will remain at rest. Objects in motion will continue to MOVE in a
STRAIGHT line path with a CONSTANT speed, unless acted upon by a net force or
UNBALANCED force.
Activity 6.
A.
1.
2.
3.
4.
5.
Net force causes both carts to move
Cart 2
Cart 2
Cart 2 will accelerate 2x greater than Cart 1
The acceleration of the cart also doubles.
17
B.
1.
2.
3.
4.
5.
6.
Force on cart 3 is 4x greater than that of cart 1?
4x faster
2x greater
2x faster
Acceleration also increases
Direct relationship/ acceleration increases with force
Encircle the correct term enclosed in the parenthesis to complete each statement in the
tale below.
Acceleration is (directly, inversely) proportional to net force. This means that
increasing the net external force applied to an object will (decrease, increase) the
object’s acceleration. When force is doubled, acceleration is (doubled, halved). When
force is decreased four times, acceleration (increases four times, decreases four times).
Activity 7.
A.
1.
2.
3.
4.
Cart 1
Cart 1 will gain twice as great as the acceleration of Cart 2.
Mass
Acceleration is halved
1.
2.
3.
4.
5.
4x greater
4x slower
2x greater
2x slower
Acceleration decreases
B.
Encircle the correct term enclosed in the parenthesis to complete each statement in the
box below.
Acceleration is (directly, inversely) proportional to mass. This means that increasing
the mass an object will (decrease, increase) the object’s acceleration. When mass is
doubled, acceleration is (doubled, halved). When mass is decreased four times,
acceleration (increases four times, decreases four times).
18
Activity 8.
1. 0.6 m/s2
2. 12 N
3. 5 kg
4. 5m/s2
Activity 9
1. A net force causes an object to move, stop, slow down, speed up, and/or change direction.
Net force causes acceleration.
2. Net external force directly affects the object’s acceleration. When Fnet is increased,
acceleration increases.
3. Mass inversely affects acceleration. When mass is increased, acceleration decreases.
Prepared by:
ERIC B. PASION
Cagayan National High School
19
SCIENCE 8
Name of Learner:
Grade Level:
Section:
Date:
LEARNING ACTIVITY SHEET
Newton’s Third Law of Motion
Background Information for the Learners:
Read the selection below:
Paramedic
Mike Sibal was born ten weeks early and in need of a trustworthy doctor. His
parents found Jose Rapatan, MD, a pediatrician who stayed with the baby for two
nights after he came down with a life-threateningly high fever. Thirty years later and all
grown up, Sibal, a paramedic, was called in to help at the site of a car wreck. The car
was on fire with a man still stuck inside. After firefighters helped put out the flames and
Jaws of Life opened the car, Sibal brought the injured man into an ambulance. He
learned the rescued victim’s name was Jose Rapatan—the very same Jose Rapatan
who’d saved his life as a baby.
What is the moral of the story? If you encountered a situation similar to helping a
certain person, would you also extend your service without hesitation?
Take note of what the comic strip is saying.
Do you want to understand why this is happening?
Scientifically, one’s action and its reaction is explained by the force around us. A
force is always part of a mutual action that involves another force.
Basically, force is a push or a pull. A mutual action is an interaction between one
thing and another.
Why do forces always occur in pairs?
Newton’s third law of motion states that whenever one object exerts a force on a
second object, the second object exerts an equal and opposite force on the first object.
20
Newton’s third law describes the relationship between two forces in an interaction
which has the following properties:
Identifying Action and Reaction
When action A exerts force on B, the reaction is simply B exerts a force on A. Look at
the examples in the following figures.
ACTION
Action: The tower
exerts a
weight on the
earth
Reaction: The earth
exerts a
normal force
to support the
tower
REACTION
REACTION
REACTION
Action: Tire pushes the road
Reaction: The road pushes the tire
21
ACTION
DID YOU KNOW?
Understanding how a helicopter gets its lifting force
Competency (Code): Infer that when a body exerts a force on another, an equal amount of
force is exerted back on it (S8FE-Ia-16)
ACTIVITY 1. What’s Your Action and Reaction?
Directions: Identify from the situation the ACTION and its corresponding REACTION.
Write down the Action and the Reaction Forces on the space provided on the right side of
each illustration.
To identify a pair of action-reaction forces, first identify the interacting objects A and
B, and if the action is A on B, the reaction is B on A. There is a simple recipe for treating
action and reaction forces: First identify the interaction. Let’s say one object, A, interacts
with another object, B.
Second, the action and reaction forces are stated in the form: Action: Object A exerts
a force on object B. Reaction: Object B exerts a force on object A.
1.
A bird while flying pushes the air downwards
with the help of its wings. The air pushes the
bird upwards for lift.
22
2.
A man is propelled upward and then down into the
swimming pool as he jumps on the diving board.
He exerts a downward force on the diving board
and the diving board simultaneously exerts an
equal force on the man but in the upward direction.
3.
Walking is possible- as you walk, you exert a force
against the floor (down and backward) and the
floor exerts a force back (up and forward), causing
you to move forward.
4.
A fireman has to hold on tightly to a fire hose. The
hose will fly backwards as water shoots out from it.
5.
The swimmer pushes against the water while the
water pushes back on the swimmer and pushes her
forward.
23
Activity 2. The Direction of Your Reaction
Directions. Consider the following figure. Draw a counterpart arrow that illustrates the
direction of the reaction force.
1.
6.
Action: Head bumps ball.
Reaction:
Action: Hand pulls on flower
Reaction:
2.
7.
Action: Windshield hits bug
Reaction:
Action: Athlete pushes barbell upward
Reaction:
3.
8.
Action: Fist hits wall
Reaction:
Action: Compressed air pushes balloon
surface upward
Reaction:
4
9.
Action: Hand touches nose
Reaction:
5.
Action: Air rushes down
Reaction:
10.
Action: Bat hits ball
Reaction:
Action: Foot pushes down
Reaction:
24
Activity 3. Puzzled with Forces
Directions. Fill in the crossword puzzle with the words missing from the sentences below.
Match the number of the sentence to the boxes placed across or down the grid.
1
2
3
4
5
6
7
8
9
10
Across
3. Force acting on one direction
4. A man shoots a rifle and the force of the shot
results in recoil. The magnitude
of the force on the rifle
the magnitude of force on the bullet.
9. The force that acts on an object to stop
its motion
10. Reaction always go in the
direction of the action
Down
1. The force that pull things toward Earth
2. A book exerts a force of 2N downwards,
into a chair that exerts a force of 5N
downwards to the floor it stands on. What is
the force that the floor exerts upwards on
the chair?
5. For every action there is an equal and
opposite reaction
6. Force acting on the opposite direction
7. Forces always come in
.
8. A push or a pull
25
Activity 4. Force of Choices
Directions: Choose the answer from the given questions. Encircle the letter of the correct
answer.
1.
2.
3.
4.
5.
6.
7.
What could correctly complete the following statement? “A force interaction requires at
least a(n)
”
A. Action force.
B. Pair of force.
C. Reaction force.
D. Single force.
What wouldcorrectly fill the following statement? “Whenever one subject exerts a force
on a second object, the second object exerts a force on the first that is
”
A. in the same direction and equal in magnitude at the same time.
B. in the same direction and lesser in magnitude at the same time
C. opposite in direction and equal in magnitude at the same time.
D. opposite in direction and greater in magnitude at the same time
What object will provide a forward motion force to a motor scooter along a higway
which is a reaction from the vehicle’s tires?
A. Engine
B. Fuel
C. Road
D. Steering Wheel
What is the direction of gravity against a person when he jumps from the ground?
A. Downward
B. Upward
C. To the left
D. To the right
What will happen if a net force acts on a horse while pulling a wagon?
A. The horse-wagon system accelerates.
B. The horse-wagon system does not move.
C. The horse-wagon system is pulled backwards.
D. The horse will accelerate but the wagon will be steady.
At a pizza shop, the cook throws the pizza dough in the air. On what factor will the
amount of force that the cook exerts on the dough depend on?
A. Brand label of the dough
C. Mass of the dough
B. Color of the dough
D. Strength of the dough
While driving down the road, a firefly strikes the windshield of a bus and makes a quite
obvious mess in front of the face of the driver. The firefly hit the bus and the bus hits the
firefly. Which of the following statements is correct?
A. The force of the firefly on the windshield is zero.
26
B. The force of the firefly is lesser than the force of the bus.
C. The force of the firefly is greater than the force of the bus.
D. The force of the firefly and the bus have no difference in magnitude.
8. Which of the following situation best describes Newton’s Third Law of Motion?
A. A rifle recoils when fired.
B. Occurrence of high and low tides.
C. A follow through is needed when a golfer hits the ball with a golf club.
D. A chocolate vendor has to move with the bus as he jumps off the bus.
9. Trisha, who has a mass of 30 kg stands on platform. What is the magnitude of force
called Normal Force does the platform exert on Trisha?
A. 9.8 N
C. 257.5 N
B. 30.00 N
D. 294.00 N
27
10. Two 100-N weights are attached to a scale called spring balance as shown. What is the
reading on the scale?
A. 0 N
B. 50 N
C. 150 N
D.200 N
Activity 5- Decode the Forces in Your Life
Life is a matter of decoding the forces around us. If you push hard on the world, the
world pushes hard on you. If you touch the world gently, the world would touch you gently
in return. Since you have mastered what the Newton’s Third Law of Motion says, it is now
time to apply it to real life situations.
Directions: Decrypt the following cryptograms. The titles are the clues of the phrases that
you need to crack. These phrases are quotes which exhibits life’s action-reaction forces.
Enjoy decoding!
1. Gaps, stimulus and reactions
28
2. Spiritual Reaction of a person
3.
Emotional forces
4.
To accept or to surrender
29
5. Self-Realization
Reflection:
In the third law of motion, if there is an action, there will be a reaction. In real-life
situations, good deeds can yield the same. Thus, be reminded of the golden rule: do unto
others what you want others to do unto you (Arevalo, R., 2017)
1. I learned that
2. I enjoyed most on
3. I want to learn more on
30
References:
“Action = Reaction.” 8TH GRADE SCIENCE. Accessed June 3, 2020.
https://clarkscience8.weebly.com/action--reaction.html.
Arevalo, Ryan L. Diwa Senior High School Series . Makati City, Philippines: Diwa Learning
Systems Inc, 2017
“Comic Strip Starters: MakeBeliefxComix.com.” Make Beliefs Comix, September 15, 2019.
https://www.makebeliefscomix.com/original-comic-strip-starters/.
Google Search. Google. Accessed June 3, 2020. https://www.google.com/search?q=action
and reaction quotes life&tbm=isch&source=iu&ictx=1&fir=mOsjoI2TQZ68M:,4rj3NU2i9_Ou3M,_&vet=1&usg=AI4_kS_b0khIiQMlHNWktiVifEdKKFf_w&sa=X&ved=2ahUKEwju3428lt3pAhWpwos
BHRVkB7EQ9QEwB3oECAoQIg#imgrc=mOsjoI2-TQZ68M:
Hewitt, Paul G. Conceptual Physics. Boston: Pearson, 2015.
Padua, Alicia L, and Ricardo M Crisostomo. Practical and Ecxplorational Physics Modular
Approach. Edited by Lilia M Rabago. Vibal Publishing House, Inc., 2003
“Reaction Sayings and Quotes.” Reaction Sayings and Reaction Quotes | Wise Old Sayings.
Accessed May 27, 2020. https://www.wiseoldsayings.com/reaction-quotes/.
“The Law of Action-Reaction (Revisited).” The Physics Classroom. Accessed May 28, 2020.
https://www.physicsclassroom.com/class/momentum/Lesson-2/The-Law-of-ActionReaction-(Revisited).
“TOP 25 ACTION AND REACTION QUOTES: A-Z Quotes.” A. Accessed June 3, 2020.
https://www.azquotes.com/quotes/topics/action-and-reaction.html.
“Welcome to Discovery Education's Puzzlemaker! Create Crossword Puzzles, Word
Searches, Mazes, and Other Puzzles for Your Classroom Today!” Welcome to
Discovery Education's Puzzlemaker! Create crossword puzzles, word searches,
mazes, and other puzzles for your classroom today! Accessed June 3, 2020.
http://puzzlemaker.discoveryeducation.com/.
Answer Key:
Activity 1
1. Action: A bird wings pushes the air downwards.
Reaction: The air pushes the bird upwards for lift.
2. Action: The man exerts a downward force on the diving board.
Reaction: The diving board simultaneously exerts an equal force on the man but in the
upward direction.
3. Action: A person exerts a force against the floor (down and backward).
31
Reaction: The floor exerts a force back (up and forward), causing you to move forward.
4. Action: A fireman has to hold on tightly to a fire hose
Reaction: The hose will fly backwards as water shoots out from it.
5. Action: The swimmer pushes against the water
Reaction: The water pushes back on the swimmer and pushes him forward.
Activity 2
1.
6.
Action: Hand pulls on flower
Reaction: Flower pulls on hand
Action: Head bumps ball.
Reaction: Ball bumps head
2.
7.
Action: Windshield hits bug
Reaction: Bug hits windshield
Action: Athlete pushes barbell upward
Reaction: Barbell pushes down
3.
8.
Action: Fist hits wall
Reaction: Wall hits fist
Action: Compressed air pushes balloon
surface outward
Reaction Balloon surface pushes
compressed air inward
4
9
Action: Air rushes down
Reaction: Balloon goes up
Action: Finger touches nose
Reaction: Nose touches finger
5.
10.
Action: Bat hits ball
Reaction: Ball hits bat
Action: Foot pushes down
Reaction: Floor pushes up
32
Activity 4
1. B
2. C
3. C
4. A
5. A
6. C
7. D
8. A
9. C
10. A
Activity 5
1. Create gaps between stimulus and reaction and the gap will show you the path by
Amit Ray
2. God’s reaction towards things is different from ours and He wishes that our reaction
will line up with His by Sunday Adelaja
3. How you react emotionally is a choice in any situation. by Judith Orloff
4. Acceptance is an active response to a temporary situation; surrender is a passive
reaction to a situation that you think will last forever by Oli Anderson
5. If a man realizes who he is, he will not react to the negative things surrounding him
by Sunday Adelaja.
Prepared by:
RIZZA C. BALORAN
MARIA LORESA J. TUMANGUIL
Tuguegarao City Science High School
Illustrator:
TRISHA ELIZABETH J. TUMANGUIL
33
SCIENCE 8
Name of Learner:
Grade Level:
Section:
Date:
LEARNING ACTIVITY SHEET
Potential Energy and Kinetic Energy
Background Information for the Learners:
Read the comic strips.
34
Credits:
https://www.storyboardthat.com/(https://www.storyboardthat.com/portal/storyboards/sheela0202
88/class-storyboard/potential-and-kinetic-energy3)
Learning Competency and Code: Identify and explain the factors that affect the Potential
Energy and Kinetic Energy of the object. (S8FE-Id-22)
35
Activity 1:
How Potential am I?
Potential energy= weight x height (P.E =w x h)
Note: Since weight=mass x acceleration due to
gravity, P.E can be written also as (P.E =m x g x h)
The units used are:
Energy =Joules, J
Weight= Newtons, N
Height= meters, m
Mass= Kilograms, kg
Acceleration due to gravity= (9.8 m/s2)
Directions: Study table A and table B below and analyze the different quantities given. Then,
answer the questions that follow.
Table A: PE of the object when the mass varies while the height remains the same
Mass, kg
Acceleration due to gravity,
m/s2
Height, m
1
2
3
9.8
9.8
9.8
2
2
2
P.E
(P.E=mgh),
J
19.6
39.2
58.8
Table B: PE of the object when the mass remains the same as height increases
Mass, kg
Acceleration
due to gravity,
m/s2
Height, m
P.E
(P.E=mgh),
J
2
9.8
1
19.6
2
9.8
2
39.2
2
9.8
3
58.8
1: In table A, what happens to the P.E of the object when mass increases but the height of the
object remains the same?
2: In table B, what happens to the P.E of the object when height increases but the mass of the
object remains the same?
3: What are the factors that affect the P.E of an object?
36
4: How can mass/weight and height affect the P.E of an object?
5: What is the relationship of mass/weight and height to the P.E of an object?
6: Give at least two (2) situations where we can apply P.E in our real life.
37
Activity 2: Kick Here! Kick There! KINETIC Anywhere!
Kinetic energy= ½ mass x velocity2
In symbol: (K.E=1/2 mv2)
The units used are:
Mass (m) = kilograms, kg
(Velocity)2 (v2) = meter2/second2,
m2/s2
Directions: Study table C and D below and analyze the different quantities given. Then,
answer the questions that follow.
Table C: KE of the object when the mass increases and the square of its velocity
remains the same
Mass, kg
(Velocity)2,
m2/s2
0
1
2
2
2
2
K.E
(K.E=1/2 mv2),
J
0
2
4
Table D: KE of the object when the mass remains the same while the square of
its velocity increases
1.
Mass, kg
(Velocity)2,
m2/s2
2
2
2
0
2
4
K.E
(K.E=1/2 mv2),
J
0
4
16
In table A, what happens to the K.E of the object when mass increases but the velocity
of the object remains the same?
2. In table B, what happens to the K.E of the object when the velocity doubles but the
mass of the object remains the same?
3. What happens to the K.E of an object when the object is massless? When velocity is
zero? What can you infer in this situation?
38
4.
What are the factors that affect the K.E of an object?
5. How can mass and velocity affect the K.E of an object?
6. What is the relationship of mass and velocity to the K.E of an object?
7. Give at least two (2) applications/situations where we can apply K.E in our real life.
_
Activity 3: Jack and Hill
Directions: Identify the relationship between Kinetic Energy and Potential Energy of the
cyclist at each position as shown in the illustration below. Choose the letter of your answer
from the given choices.
2
1
3
Credits: https://www.google.com/search?q=comic+strip+on+potential+and+kinetic+energy+png
A. K.E
increases while
P.E decreases.
C. K.E decreases
while P.E
increases.
B. P.E is at a
minimum.
1.
2.
3.
4.
39
D. P.E is at a
maximum.
Activity 4: Game of Energetics
Adapted from: theeducationcenter.com by PINTEREST
Directions: In the following competition, Team Potential and Team Kinetic will each try to
emerge as the winner. To find out who comes out on top, read the description of each
player’s energetic action. Then check the correct box to indicate which team can take credit
for the action. When finished, total the scores and show the final results on the scoreboard.
ENERGY SCOREBOARD
POTENTIAL
Team Potential
KINETIC
Team Kinetic
1. Player 11’s rock is at the top of a hill.
2. Player 22 aims a stretched rubber band at the target.
3. Player 33 shoots her rubber band toward the goal.
4. Player 14 waits, with his bow pulled back, to release
the arrow.
4. Player 35 kicks the football.
5. Player 26 hits the golf ball with his club.
6. Player 17 releases the arrow from his bow.
7. Player 48 pushes the rock over the cliff
8. The pitcher stands with his arm above his head and
the ball in his hand.
10. Player 50 is holding a 2-kg rock 1.5m above the
floor.
40
Activity 5: PE and KE are PROBLEMatic
Directions: Solve the following problems. Show your solution.
1. What is the potential energy of a rock that weighs 150 Newtons that is sitting on top
of a hill 200 meters high?
2. A 1500-kg automobile is traveling at a velocity of 120 m/s. How much kinetic energy
does it possess?
3. A flower pot has a mass of 8kg on a window 30 meters from the ground. What is the
gravitational potential energy of the flower pot in joules?
4. A toy car that weighs 15 kg is rolling down a hill with a velocity of 4.5 m/s. What is
the kinetic energy of the toy car?
5. A 25 kg block is raised by a crane 4 meters above the ground. What is the potential
energy of the block?
41
REFLECTION:
1. I learned that
2. I enjoyed most on
3. I want to learn more on
42
References:
Campo, Pia C., et.al. 2003. Science – Grade 8. Learner’s Module. Pasig City. Department of
Education.
CK12 Foundation. “Potential Energy.” Accessed May, 2020. https://www.ck12.org/c/physics/
potential-energy/lesson/Potential-Energy-PHYS/?referrer=concept_details.
Storyboard That. “Digital Storytelling.” Accessed May,2020. https://www.storyboardthat.
com/.
43
Answer Key:
Activity #1: How Potential am I?
1.
2.
3.
4.
5.
6.
The P.E also increases.
The P.E also increases.
Mass/Weight and height.
If the mass/weight and height increases, the PE also increases.
Mass/Weight of an object and its height is directly proportional to the P.E.
Sample answers:
A yoyo before it is released.
The wick in a candle.
Fireworks before they are launched
Activity #2: Kick here! Kick There! KINETIC anywhere!
1. If the mass is 0, the K.E is also zero.
If the mass increases, the K.E also increases.
If the mass doubles, the K.E also doubles.
2. If the velocity is 0, the K.E is also zero.
If the velocity increases, the K.E also increases.
If the velocity doubles, the K.E increases by a factor of four. That is because velocity
is squared in the equation.
3. Mass and velocity.
4. If the object is massless, therefore the K.E is zero.
If the object is not moving (zero velocity), therefore the K.E is also zero.
If the mass increases, the K.E also increases.
If the velocity doubles, the K.E increases by a factor of four.
5. Mass and velocity is directly proportional to the K.E of an object.
6. Sample answers:
A moving tricycle or car.
A flying paper airplane.
A person riding a skateboard.
Activity #3: Jack and Hill
1. C
2. D
3. A
4. B
44
Activity #4: Game of Energetics
1. P.E
6. K.E
ENERGY SCOREBOARD
2. P.E
7. K.E
POTENTIAL
KINETIC
3. K.E
8. K.E
5
5
4. P.E
9. P.E
5. K.E
10. P.E
Activity #5: PE and KE are PROBLEMatic!
1. P.E=30,000 Joules
2. K.E= 90,000 Joules
3. P.E=2352 Joules
4. K.E= 151.875 Joules
5. P.E =980 Joules
Prepared by:
SHEELA A. APOSTOL
EDGAR A. SADDUL
Tuguegarao City Science High School
45
SCIENCE 8
Name of Learner:
Grade Level:
Section:
Date:
LEARNING ACTIVITY SHEET
When Hotter, Faster or Slower?
Background Information for the Learner
Sound waves need a medium to be transmitted. The medium could be a solid, liquid or gas.
Its speed through the medium is affected by some factors. One of the factors is temperature. When
sound travels through dry air, its speed increases by 0.6 m/s per 1oC increase in temperature. The
speed of sound at a certain temperature in air can be computed using the formula: v = 331m/s +
0.6m/s/oC (T). Where v is the speed of sound in air, 331 m/s is the speed of sound at 0 oC, 0.6m/s/oC is
the increase in speed of sound per oC increase in temperature, and T is the temperature of air. In your
past lessons about sound, you have learned that sound energy travels from one particle to another. As
the temperature increases, the particles vibrate faster resulting to more collisions per unit time. With
more collisions per unit time, sound energy is transferred more efficiently, and travel quickly.
In this activity, you will be investigating the effect of temperature to the speed of sound by
doing different activities.
Learning Competency and Code
Investigates the effect of temperature to speed of sound through fair testing (S8FE – Ie – 25)
46
Activity 1. 3 Pics, 1 Concept
Directions: The diagram below shows the air temperature in some areas, and the speed of sound.
Study the diagram and answer the questions that follow.
Source: www.nde.ed.org/EducationResources/HighSchool/Sound/tempandspeed.html
Questions:
1.
What is the speed of sound at the lowest temperature given in the diagram?
2.
What is the speed of sound at the highest temperature given in the diagram?
3.
4.
5.
At what temperature where sound travels the slowest?
At what temperature where sound travels fastest?
How does temperature affect the speed of sound?
47
Activity 2. Solve for v
Directions: The table below shows some cities in the world and their recorded air temperature in a
certain time. Using the formula v = 331m/s + 0.6m/s/oC (T), calculate the speed of sound in each
given location. Record your answers in the table. Show your complete solution. Start with the given
quantities, required or unknown, formula, solution, and final answer. A rubric will be used to evaluate
your answers. Then, answer the questions that follow.
Table 1. Speed of sound in some cities in the world at different temperature
Location
Temperature in ºC
Sapporo, Japan
-4
Madrid, Spain
6
Wuhan, China
15
Tuguegarao City, Philippines
40
Write your complete solutions here:
Sapporo, Japan
Madrid, Spain
Given:
Given:
Required:
Required:
Formula:
Formula:
Solution:
Solution:
Answer:
Answer:
48
Speed (v) of sound in m/s
Wuhan, China
Tuguegarao City, Philippines
Given:
Given:
Required:
Required:
Formula:
Formula:
Solution:
Solution:
Answer:
Answer:
Questions:
1.
2.
3.
a. What city is relatively the hottest?
b. What is the speed of sound in this city?
c. Is it relatively the fastest? or slowest?
a. What city is relatively the coldest?
b. What is the speed of sound in this city?
c. Is it relatively the fastest? or slowest?
What is the effect of temperature to the speed of sound in air?
Rubric for the problem solving:
5
4
3
2
1
Five parts,
namely Given
quantity,
Required or
unknown,
Formula,
Solution, and
Final answer are
complete and
properly written.
Four parts are
complete and
properly written
Three parts are
complete and
properly written
One or Two
parts are
complete and
properly written
No part is
properly written
Each quantity
involved has
correct unit of
measurement
Each quantity
involved has
correct unit of
measurement
Three or four
quantities have
correct unit of
measurement
One or two
quantities have
correct unit of
measurement
Quantities have
no unit of
measurement
49
Activity 3. Hotter, Faster
Directions: Sound waves also travel through solid, and liquid like water. The table below shows the
speed of sound in water at different temperature. Study the data, and answer the questions that follow.
Table 2. Speed of sound in water at different temperature
Temperature in ºC
Speed of Sound in water (m/s)
0
1402
20
1482
100
1543
Questions:
1.
What happens to the speed of sound in water when the temperature increases?
2.
What happens to the speed of sound in water when the temperature decreases?
3.
Based on the table, what is the effect of temperature to the speed of sound in water?
50
Activity 3. Hotter, Faster
Directions: Sound waves also travel through solid, and liquid like water. The table below shows the
speed of sound in water at different temperature. Study the data, and answer the questions that follow.
Table 2. Speed of sound in water at different temperature
Temperature in ºC
Speed of Sound in water (m/s)
0
1402
20
1482
100
1543
Questions:
1.
What happens to the speed of sound in water when the temperature increases?
2.
What happens to the speed of sound in water when the temperature decreases?
3.
Based on the table, what is the effect of temperature to the speed of sound in water?
51
Activity 4. #Relationship
Directions: Given the data in Table 3 below, draw the graph properly and find out the relationship
between the Temperature and the Speed of Sound. A Rubric will be used to check your graph.
Table 3. Speed of sound at different temperature.
Temperature in oC (Dry Air)
Speed of Sound in m/s
0
331
9
336
22
344
30
349
44
357
Speed of Sound
Relationship Between Temperature and Speed of Sound
Temperature (oC)
Questions:
1.
What is the shape of the graph?
2.
How does temperature affect the speed of sound?
3.
How does the speed of sound related to the temperature of a medium?
52
4.
5.
6.
At what temperature where the particles of air vibrate the fastest?
At what temperature where the particles of air vibrate the slowest?
Explain your answer in number 4 and 5 briefly.
7.
At what condition where the speed of sound becomes zero? What is its possible implication?
Rubric for the graph
5
4
3
2
1
Numbers in the X
and Y axes are
properly scaled.
Numbers in the X
and Y axes are
properly scaled.
Numbers in the X
and Y axes are
properly scaled.
Numbers in
either X or Y
axes are properly
scaled.
Numbers in both
X and Y axes are
not properly
scaled.
5 data points are
properly plotted.
4 data points are
properly plotted.
3 data points are
properly plotted.
2 data points are
properly plotted.
1 or no data point
is properly
plotted.
Line that best fits
the data points is
properly drawn.
Line that best fits
the data points is
properly drawn.
Line that best fits
the data points is
properly drawn.
A line is drawn
from one point to
another point.
No line is drawn
Reflection:
1.
I learned that
2.
I enjoyed most on
3.
I want to learn more on
53
References:
Campo, Pia C., et. al. 2003. Science-Grade 8. Learner’s Module. Pasig City. Department of
Education.
Young, Hugh D. and Freedman, Roger A. 2002. University Physics with Modern Physics. Singapore
629733. Pearson Education Asia Pte Ltd.
www.nde.ed.org/EducationResources/HighSchool/Sound/tempandspeed.html
54
Answer Key:
Activity 1. “3 Pics 1 Concept”
1.
2.
3.
4.
5.
What is the speed of sound at the lowest temperature given in the diagram? 330.4 m/s
What is the speed of sound at the highest temperature given in the diagram? 358.0 m/s
At what temperature where sound travels the slowest? - 1 ºC
At what temperature where sound travels fastest? 45 ºC
How does temperature affect the speed of sound? The higher the temperature, the faster
the speed of sound; or The lower the temperature, the slower the speed of sound
Activity 2. “Solve for v”
Sapporo, Japan
Madrid, Spain
Given: T = -4 ºC
Given: T = 6 ºC
Required: v =?
Required: v =?
Formula: v = 331m/s + 0.6m/s/oC (T)
Formula: v = 331m/s + 0.6m/s/oC (T)
Solution: v = 331m/s + 0.6m/s/oC (-4 ºC)
Solution: v = 331m/s + 0.6m/s/oC (6 ºC)
Answer: v = 328.6 m/s
Answer: v = 334.6 m/s
Wuhan, China
Tuguegarao City, Philippines
Given: T = 15 ºC
Given: T = 40ºC
Required: v =?
Required: v =?
Formula: v = 331m/s + 0.6m/s/oC (T)
Formula: v = 331m/s + 0.6m/s/oC (T)
Solution: v = 331m/s + 0.6m/s/oC (15 ºC)
Solution: v = 331m/s + 0.6m/s/oC (40 ºC)
Answer: v = 340.0 m/s
Answer: v = 355.0 m/s
Rubric for the problem solving:
5
4
3
Five parts, namely
Given quantity,
Required or
unknown,
Formula, Solution,
and Final answer
are complete and
properly written.
Four parts are
complete and
properly written
Three parts are
complete and
properly written
One or Two
parts are
complete and
properly written
No part is
properly written
Each quantity
involved has
correct unit of
measurement
Each quantity
involved has
correct unit of
measurement
Three or four
quantities have
correct unit of
measurement
One or two
quantities have
correct unit of
measurement
Quantities have
no unit of
measurement
55
2
1
Table 1. Speed of sound in some cities in the world at different temperature
Location
Temperature in ºC
Speed (v) of sound in m/s
Sapporo, Japan
Madrid, Spain
Wuhan, China
Tuguegarao City, Philippines
-4
6
15
40
328.6
334.6
340.0
355.0
1.
2.
3.
4.
What city is relatively the hottest? Tuguegarao City, Philippines
What is the speed of sound in this city? 355.0 m/s
Is it relatively the fastest? Or slowest? Fastest
What city is relatively the coldest? Sapporo, Japan
What is the speed of sound in this city? 328.6 m/s
Is it relatively the fastest? Or slowest? Slowest
What is the effect of temperature to the speed of sound in air?
The higher the temperature, the faster the speed of sound; or The lower the
temperature, the slower the speed of sound
Activity 3. “Hotter, Faster”
1.
2.
3.
What happens to the speed of sound in water when the temperature increases?
The speed of sound in water increases when the temperature increases.
What happens to the speed of sound in water when the temperature decreases?
The speed of sound in water decreases when the temperature decreases.
Based on the table, what is the effect of temperature to the speed of sound in water?
Sound travels faster when the temperature increases; or Sound travels slower when the
temperature decreases.
Activity 4. “#Relationship”
56
Rubric for the graph
5
4
3
2
1
Numbers in the X
and Y axes are
properly scaled.
Numbers in the X
and Y axes are
properly scaled.
Numbers in the X
and Y axes are
properly scaled.
Numbers in
either X or Y
axes are properly
scaled.
Numbers in both
X and Y axes are
not properly
scaled.
5 data points are
properly plotted.
4 data points are
properly plotted.
3 data points are
properly plotted.
2 data points are
properly plotted.
1 or no data point
is properly
plotted.
Line that best fits
the data points is
properly drawn.
Line that best fits
the data points is
properly drawn.
Line that best fits
the data points is
properly drawn.
A line is drawn
from one point to
another point.
No line is drawn
1.
2.
3.
4.
5.
6.
7.
What is the shape of the graph?
Straight line graph (slanting to the right)
How does temperature affect the speed of sound?
As the temperature increases, the speed of sound increases
How does the speed of sound related to the temperature of a medium?
Speed of sound is directly proportional to the temperature.
At what temperature where the particles of air vibrate relatively the fastest?
Particles vibrate fastest at 44 ºC
At what temperature where the particles of air vibrate relatively the slowest?
Particles vibrate fastest at slowest at 0 ºC.
Explain your answer in number 5 briefly.
The higher the temperature, the higher the kinetic energy of the particles, the faster
they vibrate.
At what condition where the speed of sound becomes zero? What is its possible implication?
The speed of sound becomes zero when the particles of a medium stop vibrating, having
zero kinetic energy. This means that no sound can travel through the medium, no sound
can reach the ears of the receiver, no sound can be heard.
Prepared by:
GEMMA U. PACAMALAN
Cagayan National High School
REOWIN PALATTAO
Gosi National High School
57
SCIENCE 8
Name of learner:
Grade level:
Section:
Date
LEARNING ACTIVITY SHEET
Colors of Light
Background Information for the Learners
Have you seen a rainbow? When can you see a rainbow?
A rainbow displays a unique band of colors. The colors we see are the result of
sunlight hitting water drops where reflection, refraction and dispersion forms a rainbow.
Water drops act as tiny prism separating sunlight into bands of colors. The colors of light are
distinguished from each other by their different wavelengths and frequencies. The colors of
light depend on their frequencies and wavelengths. Wavelength is the distance between two
identical adjacent points in a wave while frequency is the number of waves that pass a fixed
point in a unit time.
The wavelengths and frequencies of the colors of light vary. The higher the
frequency of the color of light, the greater is its energy. As the frequency of the color of light
increase, the energy also increases. Red has the least frequency with the least energy and
violet has the highest frequency and the highest energy. The spectral colors have the
following characteristics; frequency, wavelength and energy. The color of light with longer
wavelength travels slowly and has low frequency and energy. The color of light with shorter
wavelength travels faster and has higher frequency and energy.
Learning Competency and Code:
Explain the hierarchy of colors in relation to energy. (S8FE-If-27-28)
58
Activity 1. Complete Me
Directions: Unscramble the word/s to get the correct term and fill the appropriate blanks to
complete the statements below.
itwhehltig
deeps
dgbinen
loroc
repsidoin
pmetsrcur
calticriganle
flecnoiter
velewagnth
lotatlanterniflecnoiter
1. Lights of different frequencies make up
.
2.
band of colors obtained by dispersion of light.
3. Refraction is the
of light when it travels from one medium to another
of different optical densities.
4.
the process of separating light into a band of colors.
5.
occurs when the angle of incidence is greater than the
critical angle.
6.
property of light waves which is dependent on the frequency or
wavelength of radiation that reaches the eye.
7.
the angle of incidence in the denser medium resulting in
angle of refraction of 900.
8.
property of light responsible for the formation of colors.
9. The
of the different colors changes as it passes through the prism.
10.
is the turning back of light when it hits a barrier.
59
Activity 2. Who Am I?
Directions: The diagram below shows the separation of white light into different colors as it
hits the prism. Color the refracted rays. Then, answer the questions that follow.
1. What do you call the process of separating white light into its components?
2.
3.
4.
5.
Which color is bent the most?
Which color is bent the least?
What do you call the bond of colors produced?
What are the component colors of a white light?
6. What name or code could you give according to the hierarchy of colors?
Activity 3. Fact or Bluff
Directions: Study the illustrations of wavelengths below. Given the following color
descriptions, write Fact on the blank if it is true while Bluff if it is false.
VIOLET
RED
1. Violet has longer wavelength.
2. Red has shorter wavelength.
3. Violet and red have the same wavelengths.
4. Red has longer wavelength.
5. Violet has shorter wavelength.
60
Activity 4. Relate Me
Directions: Draw and color the rainbow with the corresponding bond of colors in relation
to its wavelength.
1. Which color represents the longest arc/ wavelength?
2. Which color represents the shortest arc/ wavelength?
3. What color appears at the top of the rainbow? Why?
4. What color appears at the bottom of the rainbow? Why?
5. Explain how wavelength is related in the position of colors in a rainbow?
61
Activity 5. Color Me
Directions: Color the spectrum wheel based on the given corresponding frequency,
wavelength and energy.
62
Activity 6. Fill Me
Directions: Using the illustration of Color Wheel in Activity 5, fill out the table with
the corresponding wavelength, frequency and energy.
Table 1
Frequency
Wavelength
Energy
(Hz)
(m)
(eV)
Red
Orange
Yellow
Green
Blue
Violet
Activity 7. Compare Me
Directions: Study Table 1 to answer the questions below.
1. Compare the following color bonds using the descriptions (lower, higher, shorter, and
longer).
a. Red is
in wavelength than violet.
b. Yellow is
in energy than blue.
c. Violet is
in frequency than red.
d. Red is
in energy than violet.
e. Blue is
in wavelength than red.
2. Which of the colors have the following characteristics?
a. Longest wavelength?
b. Shortest wavelength?
c. Lowest frequency?
d. Highest frequency?
e. Highest energy?
f. Lowest energy?
63
Activity 8. Link Me
Directions: Use the illustration of electromagnetic spectrum in answering the questions that
follow.
https://www.miniphysics.com/electromagnetic-spectrum_25.html
1. Does the frequencies of the colors of light increase from red to violet?
2. What did you observe about the wavelengths and frequencies of the colors of light?
3. How is frequency related to energy of colors of light?
4. What did you observe about the corresponding energies from red to violet?
5. How will you explain the heirarchy of colors in relation to energy?
Reflection:
1. I learned that
2. I enjoyed most on
3. I want to learn more on
64
References:
Campo, Pia C., et. al. 2003. Science – Grade 8. Learner’s Module. Pasig City. Department of
Education.
Rabago, Lilia M., Ph.D.,et.al. 2001. Science and Technology IV: Physics Textbook for Fourth
Year. Quezon City. Vibal Publishing House.
Sotto, R.L., et. al. 2003. Science in Today’s World: Physics. Manila: Rex Bookstore, Inc.
https://www.miniphysics.com/electromagnetic-spectrum_25.html
https://www.youtube.com/watch?v=ASEdGwpyn58&t=4s
https://www.youtube.com/watch?v=TvT3g8kU6SQ
65
Answer Key:
Activity 1- Complete Me
1. White light
2. Spectrum
3. bending
4. Dispersion
5. Total internal reflection
6. Color
7. Critical angle
8. Wavelength
9. Speed
10. Reflection
Activity 2-Who am I?
1.
2.
3.
4.
5.
6.
Dispersion
Violet
Red
Spectrum
Red, orange, yellow, green, blue, indigo, violet
ROY G BIV
Activity 3- Fact or Bluff
1.
2.
3.
4.
5.
Bluff
Bluff
Bluff
Fact
Fact
Activity 4 – Relate Me
1.
2.
3.
4.
Red
Violet
Red -- Red has longer arc / wavelength
Violet – Violet has short arc//wavelength
66
Activity 5 Color Me
Activity 6 – Fill Me
Frequency
Wavelength
Energy
(THz)
(nm)
(eV)
Red
422
700
1.77
Orange
484
620
2.00
Yellow
517
580
2.14
Green
566
530
2.34
Blue
638
470
2.6
Violet
744
400
2.95
67
Activity 7- Compare Me
1. a. longer
b. lower
c. higher
d. lower
e. shorter
2. a. Red
b. Violet
c. Red
d. Violet
e. Violet
f. Red
Activity 8- Link Me
1. Yes.
2. The wavelengths and frequencies of the colors of light vary. The wavelength
decreases from red to violet while the frequency increases from red to violet.
3. The higher the frequency of the color of light, the greater is its energy.
4. As the frequency of the color of light increase, the energy also increases. Red has the
least frequency with the least energy and violet has the highest frequency and the
highest energy.
5. The spectral colors have the following characteristics; frequency, wavelength and
energy. The color of light with longer wavelength travels slowly and has low
frequency and energy. The color of light with shorter wavelength travels faster and
has higher frequency and energy.
Prepared by:
VENIE N. DE LEON
Cagayan National High School
68
SCIENCE 8
Name:
Grade Level:
Date:
Score:
LEARNING ACTIVITY SHEET
Heat and Temperature
Background Information for Learners
Heat is often associated with temperature. In a typical life, one has to cook food using
wood or other fuels like LPG. Burning fuels generate heat. Heat generated, on the other hand,
is associated with increase in temperature. However, this is not always the case. Though heat
and temperature are related to each other, they are two different concepts. The difference
between these terms has something to do with the movement between atoms and molecules –
the kinetic energy of substances. The Kinetic Molecular Theory of matter states that matter
consists of particles that are constantly moving. Take into consideration the Figure 1 below.
Temperature =
1000C
Temperature = 1000C
Heat
Heat
A
B
Figure 1: Boiling a 500 ml of water (A) vs 100 ml of water (B)
Figure 1 above shows that regardless of the volume of water, the temperature of the
two set-ups remain the same upon reaching their boiling points. There are more water
molecules in beaker A containing 500 ml water, thus, requiring longer time for it to boil than
100 ml of water in beaker B. The higher the number of water molecules, the higher also is its
heat /internal energy.
69
Temperature is the measure of hotness or coldness of a body and is measured by the
use of thermometer (Madriaga et. al, 2013).It is the average kinetic energy which indicates the
direction in which heat flows. Heat, on the other hand, is the energy that transfers from a
body of higher temperature to another body of lower temperature through molecular
collisions and cannot be directly measured. When heat is absorbed or given off by an object,
its temperature changes. If heat is added to an object, the particles of the object move faster
and the body’s temperature increases. If heat is transferred or removed from an object, the
particles move slower and the body’s temperature decreases. As the thermal energy of a
substance increases, its particles spread out and the substance expands in a process known as
thermal expansion. Almost all materials expand when heated and contract when cooled
(Padua et.al, 2010). Moreover, phase changes occur when heat is added to or removed from
an object. Different materials also have the ability to absorb or release heat that result in
temperature change. The amount of heat required by a material to increase its temperature of
one-unit mass of a given material by one Celsius degree or by one Kelvin is called specific
heat capacity (C). Padua et. Al, 2010).
Learning Competency and Code
Differentiate between heat and temperature at the molecular level. (S8FE-Ig-29)
70
Activity 1: Word Hunt
Directions: Search the words being described in the sentences below. The answers may be
found horizontally, vertically or diagonally.
1.
2.
3.
4.
5.
6.
7.
It is a thermal sensor that measures temperature.
A process when matter changes from state to another.
A measure of the warmth of an object or substance.
A measure of relatively low temperature of an object or substance.
The energy that is contained within a system that is responsible for its temperature.
Increase in the size of a material.
The decrease in the size of a material.
Source: Word Search Puzzle. Accessed June 8, 2020. Retrieved from
http://puzzlemaker.discoveryeducation.com/code/BuildWordSearch.asp
71
Activity 2: Heat vs. Temperature
Directions: Choose the corresponding characteristics of heat and temperature on the choices
given below. Write the letter of the correct answer on the space provided.
A. It is a measure of hotness and coldness of a body.
B. It is a form of energy that flows from a hotter region to the cooler region.
C. It is measured in degree Celsius (oC), Fahrenheit (oF) or Kelvin (K).
D. It is measured in calories (cal) or Joules (J).
E. It depends on the speed of particles, the size and type of object.
F. It does not depend on the mass of the object.
Heat


Temperature
What are the
differences
between Heat
and
Temperature?




Activity 3: Modified True or False
Directions: Write TRUE if the statement is correct. Write FALSE if the statement is wrong
and change the underlined word/s to make the statement correct. Write your answer on the
space provided.
1. Liquid expands when heated.
2. Thermal expansion applies to solid and liquid.
3. Materials take up more space when heated
4. Solid expands more than liquid when heated.
5. The particles of liquid move freely when
heated.
6. Water expands when cooled.
7. Molecules move far each other during
contraction.
8. Only the spaces between particles changes
during expansion and contraction.
9. Electrical wires could sag during hot days.
10. Tight bottle cap can easily open by putting it in
hot water.
72
Activity 4: Going Phase Change
Directions: Write the letter of the missing data on the graph below showing the phase change
of water. Choose your answer on the box. Then, answer the questions that follow.
A. vaporization
D.
G. melting
B.
E. ice
C. sublimation
F. liquid
Phase change of water as heat is added
Temperature
6.
steam
100oC
5.
4.
0oC
3.
2.
1.
Heat Energy
Source: “Phase Change: Evaporation, Condensation, Freezing, Melting ...” Accessed June 4,
2020. https://spiral.ac/lesson-plan-ideas/clips/lessons/phase-change-evaporationcondensation-freezing-melting-sublimation-deposition.
1. What happens to the temperature and heat energy of a substance during a change of state?
2. What happens when heat is added once the phase change is complete?
73
3. What can you infer about the relationship between phase change and heat energy?
Activity 5: Graph It Down
Directions: Analyze the data below of the temperature change of different substances in a
given time. Using the graph, plot the time in the x-axis vs the given values for each substance
in the y-axis. Then, connect the graph of each of the three substances. Create a line graph for
each substance below and answer the questions given. Use colored pen or crayon to connect
the graph following the color coding below:
Blue - water
Yellow- sand
Red - Iron
Time (minutes)
0 (initial)
15mins
30mins
45mins
60mins
Water
25.0 oC
26.0oC
27.5oC
28.9 oC
30.0 oC
Temperature of the Substances (oC)
Sand
25 oC
30oC
35oC
40oC
45oC
Iron
25 oC
35 oC
45 oC
55 oC
65 oC
Source: “Specific Heat Worksheet Answers.” Homeschooldressage.com, February 25, 2018.
http://homeschooldressage.com/specific-heat-worksheet-answers/
A. Temperature vs. Heating Time Graph
73
B. Answer the following questions:
1. What is the order of the substances based on the time required to heat from slowest to
fastest?
2. Which of these substances require more heat to increase in temperature?
3. Which substances require more time to increase in temperature?
4. When you boil water using a pot on the stove, which heats faster, the iron pot or the water?
Explain your answer.
_
5. When you go to the beach you noticed that the sand is hotter than water although both are
exposed under the heat of the sun. Why do you think this happens?
6. Based on the graph, which of the three substances has the highest specific heat capacity?
Which substance has the lowest specific heat capacity?
Reflection:
4. I learned that
5. I enjoyed most on
6. I want to learn more on
74
References
Madriaga, Estrellita A, Meliza P Valdoz, and Jonna M Abistado. 2013. Science Links. First
Ed. Sampaloc, Manila, Philippines: Rex Book Store, Inc.
Ocampo, Pia C. et.al. 2013 Science 8 Learner's Module. 1st ed. Pasig City, Philippines:
Department of Education.
Padua, Alicia L, and Ricardo M Crisostomo. 2010. Practical and Explorational Physics.
Second ed. Quezon City, Philippines: Vibal Publishing House, Inc.
Santos, Gil Nonato C., and Alfonso C. Danac. 2006. i-Physics (Investigatory Physics).
Firsted. Sampaloc, Manila, Philippines: Rex Book Store, Inc.
Website
“Ninth Grade Lesson Introduction to Specific Heat ...” Accessed June 3, 2020. Retrieved
from https://betterlesson.com/lesson/640676/introduction-to-specific-heat
“Phase Change: Evaporation, Condensation, Freezing, Melting ...” Accessed June 4, 2020.
Retrieved from
https://study.com/academy/lesson/phase-change-evaporation-condensation-freezingmelting.html
“Specific Heat Worksheet Answers.” Homeschooldressage.com, February 25, 2018.
Retrieved from http://homeschooldressage.com/specific-heat-worksheet-answers/
“The Physics Classroom Tutorial.” The Physics Classroom. Accessed June 3, 2020.
Retrieved from https://www.physicsclassroom.com/Class/thermalP/u18l1d.cfm
Velez, Sierra. “Blendspace Created For Physical Science By Sierra Velez ...” Blendspace
Created For Physical Science. Accessed June 3, 2020. Retrieved from
https://www.tes.com/lessons/AX17cZ8TBxwrrg/blendspace-created-for-physicalscience-by-sierra-velez
“What Is Thermal Energy? (Article) | Khan Academy.” Accessed June 4, 2020. Retrieved
from
https://www.khanacademy.org/science/physics/work-and-energy/work-and-energytutorial/a/what-is-thermal-energy
Word Search Puzzle. Accessed June 8, 2020. Retrieved from
http://puzzlemaker.discoveryeducation.com/code/BuildWordSearch.asp
75
Answer Key
Activity 1: Word Hunt
1. Temperature
2. Phase change
3. Hotness
4. Coldness
5. Thermal Energy
6. Expansion
7. Contraction
Activity 2: Heat vs. Temperature
Heat- answer B, D and E
Temperature- answer A, C and F
Activity 3: Modified True or False
1. TRUE
2. Solid, Liquid and Gas
3. TRUE
4. TRUE
5. TRUE
Activity 4: Going Phase Change
A.
1. E. Ice
2. B.
6. heated
7. Move closer
8. Fact
9. Fact
10. Fact
5. A. vaporization
6. D.
3. H. melting
4. F. liquid
B.
1. During a change of state, the temperature of a substance remains constant, while the
thermal energy changes.
2. Once the phase change is complete, adding more heat causes the temperature to
increase.
3. Heat energy is needed in phase change.
76
Activity 5: Graph it Down
A. Temperature vs. Heating Time Graph
B.
1.
2.
3.
4.
Water- Sand- Iron
The water requires more heat to increase in temperature.
The water requires more time to increase in temperature.
The iron pot heats faster than the water because it requires less energy to heat up. It
has lower specific heat capacity.
5. The sand is hot and the water is cold because the sea has to absorb more heat to raise
its temperature than the sand. Water has higher specific heat capacity than the sand.
6. Water has the highest specific heat capacity and iron has the lowest specific heat
capacity.
Prepared by:
KAREN C. GACUTAN
Linao National High School
77
SCIENCE 8
Name of Learner:
Grade Level:
Section:
Score:
LEARNING ACTIVITY SHEET
Relationship between Voltage and Current
Background Information for Learners
Electricity is almost an indispensable part of our lives. Lighting, heating,
transportation, and communication are all dependent on it.
When you connect an electric fan to an outlet, you are assembling and using an
electric circuit. It consists of a source of electrical energy, connecting wires and a load.
The three electrical quantities are current, I measures in amperes(A), voltage, V
measures in volts(V) and resistance, R measures in ohms ( ).
In an electric circuit, the voltage is the work done in moving or pushing the charged
electrons (current) from one point to another in the circuit. The current in the circuit, on the
other hand, is responsible for illuminating the bulb or in rotating the electric fan as the case
maybe. The amount of current in the circuit is dependent upon the voltage applied. This
amount of current can be indicated by the intensity of brightness in the case of a lighted bulb.
Voltage, V is directly proportional to current, I, that is
V
or
I
V=kI
Where k, the proportionality constant, is the slope of the V vs I graph. This constant k
is equal to the resistance, R of the circuit, so
R = V/I
The unit of electrical resistance is defined as
R = volt (V)/ampere (A) or ohm ( )
1
= 1 V/A
The relationship between voltage, current and resistance is known as Ohm’s Law,
named after George Simo Ohm, who pioneered the study of such relation. Ohm’s law states
that current, I is directly proportional to the voltage, V and inversely proportional to the
resistance, R. In equation: I = V/R
78
Most electric circuits we see operate on more than one load called multiple load
circuits. For instance, when you turn on light in the dining room, lamps in your bedroom
remain unlighted, but if you remove one light bulb from Christmas bulbs, the other bulbs no
longer light.
Light bulbs in houses are connected differently from that of Christmas bulbs. The
connection of light bulbs at home is called parallel while the Christmas light bulbs is in
series.
A series connection has two or more loads but current flows through a single
conducting path while parallel connections has more than one path for current to flow. The
figure below shows the differences between series and parallel connections.
Fig.1: Series Connection
Fig. 2: Parallel connection
Applying Ohm’s law for series and parallel connections consider these equations
below.
Series connections
IT
=
I1
=
I2
=
I3
…
VT
=
V1
+
V2
+
V3
+…
RT
=
R1
+
R2
+
R3
+…
Parallel connections
IT
=
I1
+
I2
+
I3
+…
VT
=
V1
=
V2
=
V3
…
_1_ =
_1_ +
_1_ +
_1_ + …
RT
R1
R2
R3
This learning activity sheet will help you understand more of the relationship between
voltage and current.
Learning Competency with code
Infer the relationship between current and voltage. (S8FE-Ig-30)
79
Activity 1: Voltage vs. Current
Directions: Complete the chart below to show comparison between voltage and current.
Voltage
Current
Symbol
Unit
SI Unit
Definition
Relationship
Voltage is the cause and current is
the effect. Voltage can exist
without current.
Measuring
Instrument
Field created
An electrostatic field
Current is the same through all
components connected in series.
In a series
connection
In a parallel
connection
Voltages are the same across all
components connected in parallel.
80
Activity 2: The Brighter, the Better
Study the circuit diagrams below showing identical bulbs connected to a circuit with different
number of batteries. Then, answer the questions that follow.
Figure 3.
Figure 4
.
Figure 5.
1.
Which configuration is the light brightest?
2.
Which configuration has the greatest amount of current?
3.
Which configuration is the light dimmest or least bright?
4.
Which configuration has the least amount of current?
5.
If a single battery has a voltage of I.5 volts, what is the voltage of the circuit in
figure 1?
6.
What is the total voltage of the circuit in figure 2?
7.
What is the total voltage of the circuit in figure 3?
81
Activity 3. “Follow Me”, Relationship between Current and Voltage
The figure below is the Experimental Set-up for finding the relationship between
voltage and current. Analyze the data taken from the experiment and do the instructions that
follow.
Fig. 6
Data taken from the experiment:
Table 1. Comparative Values of Voltage and Current at Fixed Resistance
Number of
Dry cells
Voltage,V
Current, I
Voltage,V /Current, I
(Volts)
(Ampere)
(Volt/Ampere)
1
1.5
0.15
2
3.0
0.30
3
4.5
0.45
4
6.0
0.60
1. Fill-up the fourth column of the table by dividing voltage, V by current, I.
2. Using the graph below, plot the data of voltage, V against Current,I.
82
3.
4.
5.
6.
7.
8.
Draw a line of best-fit using the plotted points.
Describe the graph?
What does the graph indicate?
What becomes of current, I as the voltage, V is increased?
What becomes of current, I as the voltage, V is decreased?
How will you describe the quotient when you divide voltage by current in column
4 of Table 1?
9. What electrical quantity represents this in the circuit?
10. What can you infer/conclude about the relationship between voltage and current
for the same/constant load or resistor?
Activity 4: Oh My Ohm’s Law
Directions: Solve the following problems applying Ohm’s Law in the circuit. Show your
complete solution. Start with the given quantities, required or unknown, formula, solution, and final
answer. A rubric will be used to evaluate your answers.
1.
How much current flows in an electric iron having a resistance of
20
when
connected across 220-V line?
2.
An electric heater uses 4A when 220-V are applied to its terminals. Determine its
resistance.
83
3.
What is the voltage across an electric hot plate which is draws 11A from the line
when its hot resistance is 20 ?
4.
What is the resistance of the coil of wire in an electric stove if it is connected to a
220V line and the current passing through it is 8A?
5.
How much current flows through a lamp with a resistance of 75
when it is
connected to a 220V line?
6.
What is the resistance of a lamp which allows 10.9A when 220V is applied to it?
7.
How much current would a 12
8.
A resistor is connected to a 12V battery. The ammeter in the circuit reads 2A. What is
the value of the resistance?
bread toaster draw when connected to a 220V outlet?
84
9.
If the voltage in the circuit were doubled, what would happen to the current in the
circuit?
10. If current in the circuit doubles of the same voltage, what will happen to the resistance
in the circuit?
Activity 5. Resistivity Affects Conductivity
As electrons flow through a conductor, they collide with the vibrating
atoms of the conductor and these electrons transfer part of their energy to the
atoms resulting to kinetic energy increases as manifested in the increase in the
temperature of a conductor. The collision of the electrons with the atoms limits
the amount of current in the conductor and this property of material is called
resistivity which describe as measure of the material’s resistance to the passage
of current. On the other hand, conductivity is the degree to which a specified
material conducts electricity.
Directions: Use the table below to answer the questions that follow.
Table 2: Resistivity of some materials at 200C.
Material
Silver
Copper
Gold
Aluminum
Tungsten
Steel
Mercury
Nichrome
Carbon
Resistivity (
1.47 x 10-8
1.72 x 10-8
2.44 x 10-8
2.63 x 10-8
5.51 x 10-8
20.0 x 10-8
95.0 x 10-8
100.0 x 10-8
3.5 x 10-5
Source: Young, Hugh D. and Roger A freedom. University Physics with Modern Physics. 11th
Ed. Pearson Wesley. 2004
1. Which of the given materials have the least resistivity?
85
2. Which of the given materials have the greatest resistivity?
3. Explain why silver and gold are not used as household wirings despite of having the
least resistivity.
4. Why is tungsten used as filament in lamps?
5. Why are copper wires used in household wiring?
Activity 6. Connect Pa More
Directions: Study the figures below to answer the following questions.
Figure 7a
Figure 7b
1.
When you connect the four bulbs to a 12V power supply switch in series as shown in Figure
7a and turn the switch on, what happens to the other bulbs when you unscrew one light bulb?
2.
What if you will screw the one light bulb in Figure 7a, what do you observe?
3.
How do you describe this type of connection?
4.
When you connect the three bulbs to a 12V power supply as shown in Figure 7b and turn the
switch on, what happens to the other bulbs when you unscrew one light bulb?
5.
What if you will screw the one light bulb in Figure 7b, what do you observe?
86
6.
How do you describe this type of connection?
7.
What is the difference between series connection and parallel connection based on your
observations from the two set up?
_
8.
What kind of connection is most practical at home? Why?
9.
Why are electric meters connected in series with the rest of the circuits in the house?
10. Why is the main switch connected in series with the rest of the circuits in the house?
Activity 7. Computation in a Connection
Directions: Perform the indicated operations. Write the equations and solve for the unknown
quantity.
1. Suppose there are four 30
bulbs are connected in series connected to a 220V line,
what is the current in the circuit? Find the voltage drop in each of the four 30
bulbs.
2. You have five appliance connected in series as shown in the figure below. The
refrigerator has a resistance of 20 , the TV set 10 , the radio 5 , the flat iron 75
and the electric stove 55 , what is a( total resistance in the circuit b) total current
c) voltage drop in each appliance
87
a. total resistance in the circuit
b.
total current
c. voltage drop in each appliance
3. Using the figure below, solve for:
a. Resistance of the combination
b. Current through the ciruit
88
c. Current through each resistor
d. Voltage across each resistor
4. Refer to the figure below to solve for:
a. Resistance of the combination
b. Current through the combination
89
c. Current in each resistor
d. Voltage across each resistor
5. Consider the circuit below, determine the following:
a. Voltage across each load,
b. Current through each load,
90
c. Total current through the circuit, and
d. Total resistance
Reflection:
1. I have learned that
2. I enjoyed most on
3. I want to learn more on
References:
Acosta Herma D et.a. 2015. Science 10 Learner's Module. 1st ed. Pasig City: Department of
Education.
Arciaga, Marco E et. Al. 2008. Exploring Science and Technology. Paranaque City: Diwa
Scholastic Press Inc.
Benetillo, Eulalia N et. al. 2009. Science and Technology IV Textbook for Fourth Year.
Revised Edition. Quezon City: Book Media Press.
91
"Current vs Voltage." Diffen.com. Diffen LLC, n.d. Web. 13 Jun
2020.< https://www.diffen.com/difference/Current_vs_Voltage >
Ocampo, Pia C. et.al. 2013. Science 8 Learner's Module. 1st ed. Pasig City: Department of
Education.
Padua L Alicia et. al. 2003. Practical and Exploration Physics. Quezon City: Vibal
Publishing House Inc.
Voltage, Current, Resistance and Ohm’s Law. Sparkfun Electronics. Accessed June 17, 2020.
https://learn.sparkfun.com/tutorials/voltage-current-resistance-and-ohms-law
Answer Key:
Activity 1: Voltage vs. Current
Voltage
Current
Symbol
V
I
Unit
V or volts or voltage
A or Amp or amperage
SI Unit
1 volt = 1 joule/coulomb.
(V=W/C)
1 ampere =1
coulomb/second.
Definition
Voltage, also called electromotive
force, is the potential difference in
charge between two points in an
electrical field.
Current is the rate at which
electric charge flows past a
point in a circuit. In other
words, current is the rate of
flow of electric charge.
Relationship
Voltage is the cause and current is
the effect. Voltage can exist
without current.
Current is the effect (voltage
being the cause). Current
cannot flow without Voltage
Measuring
Instrument
Voltmeter
Ammeter
Field created
An electrostatic field
A magnetic field
In a series
connection
Voltage gets distributed over
components connected in series.
Current is the same through
all components connected in
series.
In a parallel
connection
Voltages are the same across all
components connected in parallel.
Current gets distributed over
components connected in
parallel.
92
Activity 2: The Brighter, The Better
1.
2.
3.
4.
5.
6.
7.
Figure 5
Figure 5
Figure 3
Figure 3
1 x 1.5 volts = 1.5 volts
2 x 1.5 volts = 3.0 volts
3 x 1.5 volts = 4.5 volts
Activity 3: “Follow Me”, Relationship between Current and Voltage
Table 1. Comparative Values of Voltage and Current at Fixed Resistance
1.
Number of
dry cells
Voltage,V
Current, I
(Volts)
(Ampere)
1
1.5
0.15
10
2
3.0
0.30
10
3
4.5
0.45
10
4
6.0
0.60
10
Voltage,V/ Current, I
2&3
4. It is a straight line sloping upward to the right.
5. The graph indicates a direct relationship between Voltage and Current.
6. As the voltage, V is increased, the current, I is also increased.
7. As the voltage, V is decreased, the current, I is also decreased.
8. The answer is the same or constant
93
9. The electrical quantity being described in this constant value is called resistance, R.
10. Current, I is directly proportional or dependent to voltage, V. For the same load or
resistor, a uniform increase or decrease in voltage would result in a uniform increase
or decrease in current.
Activity 4. Oh My Ohm’s Law
1.
Given: R=20
2.
Given: I=4A, V=220V
, V=220v
Required: I
Required: R
Formula: I = V/R
Formula: R=V/I =
Solution: I = 220V/20
Solution: R = 220V/4A
Answer: I = 11V/
Answer: R = 55V/A or 55
or 11A
3.
4.
Given: I=11A, R=20
Given: V=220V, I=8A
Required: V
Required: R
Formula: V = IR
Formula: R = V/I
Solution: V=(11A)(20 )
Solution: R = 220V/8A
Answer: V = 220A.V or 220V
Answer: R = 27.5V/A or 27.5
5.
6.
Given: R=75 , V=220V
Given: I=10.9A, V=220V
Required: I
Required: R
Formula: I = V/R
Formula: R = V/I
Solution: I = 220V/ 75
Solution: R = 220V/10.9A
Answer: I = 2.93V/
Answer: R = 20.18V/A or 20.18
or 2.93A
7.
8.
Given: R=12 , V=220V
Given: V=12V, I=2A
Required: I
Required: R
Formula: I = V/R
Formula: R = V/I
Solution: I = 220V/12
Solution: R = 12V/2A
Answer: I = 18.33V/
Answer: R = 66V/A or 6
or 18.33A
94
9.The current, I in the circuit also
doubled
10.The resistance, R in the circuit was
reduced to 50%
Activity 5. Resistivity Affects Conductivity
1. Silver
2. Nichrome
3. Because melting point of silver is very low and if used as wire it could catch fire in a
house while gold is very soft to be used as wires and expensive.
4. Tungsten is used as filament in bulbs of lamps because it has the highest melting point
and lowest vapor pressure of all metals and at temperatures over 1 6500C it has the
highest tensile strength.
5. Copper wires are used in household wiring because these have very low resistances
and are good conductors. Their resistances are not affected much by temperature
changes.
Activity 6. Connect Pa More
1.
2.
3.
4.
5.
6.
7.
The other bulbs will not light up.
The four light bulbs lighted.
Series connection
The two remaining bulb will still light up
The three bulbs lighted
Parallel connection
In Figure 7a when you unscrew one bulb, the remaining bulbs in the circuit will not
light up because there is only one path for the electrons to flow in the circuit while in
Figure 7b, when you unscrew one bulb, the remaining bulbs will still lighted because
the flow of electrons in the circuit is separated.
8. Parallel connection is widely used at home because not all appliances can be used at
the same time.
9. Electric meters are connected in series with the rest of the circuit in the house to be
able to measure the total amount of electrical energy entering in the household.
10. The main switch is connected in series with the rest of the circuits in the house to be
able to control electrical energy entering the house in case of emergency
Activity 7: Computation in a Connection
1. RT = R1 + R2 + R3 + R4
RT
=
30
30
+ 30
+ 30
= 120
95
IT = VT/RT
= 220V/120
= 1.83A
IT= I1
= I2 = I3 =
I4
V1 = I1R1
= 1.83A(30
= 54.9V
V2 = I2R2
= 1.83A(30
= 54.9V
V3 = I3R3
= 1.83A(30
= 54.9V
V4 = I4R4
= 1.83A(30
= 54.9V
VT= V1 + V2 + V3 + V4 = 219.6Vor 220V
2.
a) RT = RT + RT + RT + RT
= 20
+ 10
+ 5
= 165
+ 75
+ 55
b) IT = VT / RT
= 220V/165
= 1.33A
c) Iref = V1R1 = (1.33A) ( 00 ) = 26.6V
ITV = V1R1 = (1.33A) ( 10 ) = 13.3V
Iradio = V1R1 = (1.33A) ( 5 ) = 6.65V
Iflat iron = V1R1 = (1.33A) ( 75 ) = 99.75V
Istove = V1R1 = (1.33A) ( 55 ) = 73.15V
3.
a)
1/ RT =1/ R1 + 1/R2 + 1/R3
1/ RT =1/ 2
+ 1/4
+ 1/6
96
1/ RT =11
( 11
/ 12
RT)/ 11 = 12/11
RT = 1.09
b) IT = VT / RT
= 6V / 1.09
= 5.50A
c) I1 = V1//R1
I1 = 6V/ 2
IT = 3A
I2 = V2//R2
I2 = 6V/ 4
IT = 1.5A
I3 = V3//R3
I3 = 6V/ 6
IT = 1A
d) VT = V1 = V2 = V3 = 220V
4.
a) RT = R1 + R2 + R3
= 2 +4 +6
= 12
b) IT = VT / RT
= 6V / 12
= 0.5A
c) IT = I1 = I2 = I3 = 0.5A
d) V1 = (I1 )(R1)
= (0.5A) (2 )
= 1V
V2 = (I2 )(R2)
= (0.5A) (4 )
= 2V
97
V3 = (I3 )(R3)
= (0.5A) (6 )
= 3V
VT = V1 +V2 + V3
= 1V + 2V + 3V
= 6V
5.
a) Vt = V1 = V2 = V3 = 220V
b) I1 = V1 / R1
= 220V / 240
= 0.92A
I2 = V2 / R2
= 220V / 280
= 0.78A
I3 = V3 / R3
= 220V / 300
= 0.73A
c) It = I1 + I2 + I3
= 0.92A + 0.78A + 0.73A
= 2.43A
d) 1 / RT = 1/ R1 + 1/R2 + 1/R3
1 / RT = 1/240
1 / RT
+ 1/280
+ 1/300
= 2232/21060
21060/2232 = 2232Rt/2232
99
=
Rt
98
Rubric for the problem solving:
5
4
3
2
Five parts, namely Given
quantity, Required or
unknown, Formula,
Solution, and Final
answer are complete and
properly written.
Four parts
are complete
and properly
written
Three parts
are complete
and properly
written
One or Two
parts are
complete and
properly written
No part is
properly
written
Each quantity involved
has correct unit of
measurement
Each
quantity
involved has
correct unit
of
measurement
Three or four
quantities
have correct
unit of
measurement
One or two
quantities have
correct unit of
measurement
Quantities
have no unit
of
measurement
Prepared by:
MAPHILINDO C. TURARAY
EDUARDO C. DELA ROSA
Cagayan National High School
99
1
SCIENCE 8
Name:
Section:
Date:
Score:
LEARNING ACTIVITY SHEET
Advantages and Disadvantages of Series and
Parallel Connections
Background Information for Learners
From your previous lessons about electricity, you have learned that an electrical
circuit consists of a load which can be electric bulbs or electrical appliances which consumes
electrical power; a voltage source like batteries or generator which supplies electrical energy
or a potential difference between two points within an electrical circuit allowing current to be
flowing around it; and connecting wires which provides the path for electrons or current to
flow. This electrical circuit can be connected either in series or parallel. Series connection
has only one path or route for electrons or current to flow, hence, current is the same
anywhere in the circuit. For example, if there are three bulbs connected in series, the bulbs
will have a lesser brightness since the voltage (measure of strength of electrical power) is
shared in ratio to resistance (limits or opposes the flow of electrical current). If one of the
bulbs gets busted, the other two bulbs will not work properly or do not produce light since the
flow of current is broken or disconnected. Furthermore, as the number of loads are increased
in the series circuit, the greater circuit’s resistance is produced.
Parallel connection on the other hand, has two or more paths or routes for the
flow of current. This explains that the current splits or divides among the loads such as bulbs
or appliances. In this case, the voltage across each pathway is the same throughout the circuit.
For instance, if there are three bulbs of the same wattage connected in parallel, each bulb
produces equal brightness. If one of the bulbs gets busted, the other bulbs will not be affected
and still light up because each bulb has a separate connection to a voltage source in the
circuit. In other words, if problem may occur in one of the connections in the circuit, other
connections will not be affected, hence, current will still pass through in the undisturbed
connections. This is the reason why parallel connections are preferred in household wirings
because home appliances and other electrical devices operate on the same voltage and that
loads or appliances are often switched on and off separately.
Learning Competency with code:
Explain the advantages and disadvantages of series and parallel connection in homes. (S8FE Ii - 31)
100
Activity 1: Label Matters
I. Directions. Name the two circuits according to the type of connection it represents. Write
your answer on the blank below.
A
B
a
b
e
d
f
c
f
Source: www.physicsclassroom.com
II. Directions: Answer the following questions regarding circuits A and B above.
1. In circuit A, if bulb a burns out, will bulb c still light?
Why?
2. In circuit A, if bulbs b and c burn out, will bulb a still light?
3. In circuit B, if bulb d burns out, will bulb f still light?
Why?
Why?
4. In circuit B, if bulbs d and f are missing, will bulb e still light?
Why?
5. Which do you prefer in your own household electrical wirings, series connection or parallel
connection? Why?
101
Activity 2: Ignite Your Power to Analyze
Directions: Study the illustration below and answer the questions that follow.
Source: VectorStock.com/20558187
1. If the stand fan is switched off, will the other appliances still continue to work? Why?
2. If the stand fan and television are not plugged into an outlet, will the refrigerator function?
Why?
3. If both the refrigerator and stand fan are unplugged, will the television still work? Why?
4. If all appliances are plugged into individual outlets, does it affect the voltage source?
Why?
5. Appliances at home are usually connected in parallel. What are the advantages of having a
parallel connection in household electrical connection?
102
Activity 3: Glow in the Dark
Directions: Analyze the illustrations below and answer the questions that follow.
a
b
c
1. If bulb a is removed from the circuit, will the rest of the bulbs or appliances still work?
Why?
2. What happens to the entire circuit if bulb c get busted?
3. If two more bulbs are added in the circuit, will the brightness be the same as that of the
three bulbs? Why?
4. What happens to the entire circuit if the stand fan is damaged?
5. How are the appliances and electric bulbs connected in the circuit? Is this type of
connection possible? Why or why not?
103
Activity 4: Explore Your Bright Side
Directions: Seek the assistance of your parents to inspect your household electrical
connections and answer the following guide questions.
1. Which loads or appliances are connected in series?
2. Which loads or appliances are connected in parallel?
For items 3 and 4, refer to the given situation below:
One morning, your mother is ironing your uniform with a stand fan on and a light bulb on.
Suddenly, the light bulb sparked and eventually got busted.
3. If the electric iron, stand fan and the bulb are connected in series, can your mother still
continue to iron your clothes? Why?
4. If the electric iron, stand fan and the bulb are connected in parallel, can your mother still
continue to iron your clothes? Why?
5. What are the advantages and disadvantages of series connection? How about the
advantages and disadvantages of parallel connection? Complete the table below.
Series Connection
Advantages
Disadvantages
104
Parallel Connection
Activity 5: Spark Your Best Option
Directions: Given the situations below, select one of your best choice and work for it.
1. Draw a poster about the advantages and disadvantages of series and parallel connections in
homes.
2. Create a two-minute promotional video on the advantages and disadvantages of series and
parallel connections in homes.
3. Make a rap song in the form of audio-video about the advantages and disadvantages of
series and parallel connections in homes.
Rubric for Scoring
POSTER MAKING
CATEGORY
Graphics Clarity
Graphics Originality
Graphics Relevance
Excellent
4
Good
3
Fair
2
Needs
Improvement
1
Graphics are
all in focus
and the content
easily viewed
and identified
from 6 ft.
away.
Several of the
graphics used
on the poster
reflect a
exceptional
degree of
student
creativity in
their creation
and/or display.
Most graphics
are in focus
and the
content easily
viewed and
identified from
6 ft. away.
Most graphics
are in focus and
the content is
easily viewed
and identified
from 4 ft. away.
Many graphics
are not clear
or are too
small.
One or two of
the graphics
used on the
poster reflect
student
creativity in
their creation
and/or display.
The graphics
are made by the
student, but are
based on the
designs or ideas
of others.
No graphics
made by the
student are
included.
All graphics
relate to the
topic. Most
borrowed
graphics have a
source citation.
Graphics do
not relate to
the topic OR
several
borrowed
graphics do
not have a
source
citation.
All graphics
are related to
the topic and
make it easier
to understand.
All borrowed
graphics have
a source
citation.
All graphics
are related to
the topic and
most make it
easier to
understand.
All borrowed
graphics have
a source
citation.
105
Labels
Required
Elements
Knowledge
Gained
Content Accuracy
Attractiveness
Almost all
All items of
items of
importance on importance on
the poster are
the poster are
clearly labeled clearly labeled
with labels that with labels
can be read
that can be
from at least 3 read from at
ft. away.
least 3 ft.
away.
The poster
includes all
All required
required
elements are
elements as
included on
well as
the poster.
additional
information.
Several items
of importance
on the poster
are clearly
labeled with
labels that can
be read from at
least 3 ft. away.
Labels are too
small to view
OR no
important
items were
labeled.
All but 1 of the
required
elements are
included on the
poster.
Several
required
elements were
missing.
Student can
accurately
answer all
questions
related to facts
in the poster
and processes
used to create
the poster.
Student can
accurately
answer most
questions
related to facts
in the poster
and processes
used to create
the poster.
At least 7
accurate facts
are displayed
on the poster.
The poster is
exceptionally
attractive in
terms of
design, layout,
and neatness.
5-6 accurate
facts are
displayed on
the poster.
Student can
accurately
answer about
75% of
questions
related to facts
in the poster
and processes
used to create
the poster.
3-4 accurate
facts are
displayed on
the poster.
The poster is
attractive in
terms of
design, layout
and neatness.
The poster is
acceptably
attractive
though it may
be a bit messy.
106
Student
appears to
have
insufficient
knowledge
about the facts
or processes
used in the
poster.
Less than 3
accurate facts
are displayed
on the poster.
The poster is
messy or very
poorly
designed. It is
not attractive.
VIDEO PRESENTATION
Criteria
Content
Originality
Use
Language
Excellent
Good
Fair
4
It covers all the
topics in depth
with details
and examples.
The knowledge
of the topic is
excellent.
3
It includes
basic
knowledge
about the topic.
The content
seems to be
good.
2
It includes
essential
information
about the topic
but it has 1-2
mistakes in the
facts.
The product
shows great
originality.
The ideas are
creative and
witty.
The product
shows certain
originality. It
shows the use
of new ideas
and of
shrewdness
It uses ideas
from other
people
(quoting
them0, but
there is little
evidence of
original ideas
Four spelling
or grammar
mistakes
Uses ideas
from other
people without
quoting them.
One or two
different shots,
camera angles,
sound effects,
and/or an
adequate use
of zooming
providing
variety in the
video.
The quality of
the video is not
very good but
the overall
focus was
excellent
Little effort
has been made
to provide
variety in the
video.
of There are no
mistakes in
spelling or
grammar
VideographyInterest
VideographyClarity
A lot of
different shots,
camera angles,
sound effects,
and an
adequate use
of zooming
providing
variety in the
video.
The overall
quality of the
video and the
focus were
excellent.
Three or fewer
spelling
mistakes or
punctuation
mistakes
Several (3-4)
and different
shots, camera
angles, sound
effects, and/or
an adequate
use of zooming
providing
variety in the
video.
Most of the
quality of the
video and the
focus were
excellent.
107
Needs
Improvement
1
The content
includes minor
details and it
has several
mistakes in the
facts.
More than four
spelling or
grammar
mistakes
The quality of
the video and
the focus are
not very good.
RAP MUSIC
Criteria
Accurate
Excellent
All
information
was accurate in rap
Detailed
Your rap was very
detailed. I felt like I
really knew your
person and what
he/she stood for
Thorough
Your rap and visual
covered
all
essential
beliefs
and facts about
your person
Good
Fair
There are many You
rap’s
inaccuracies
information
was
very inaccurate
Your rap gives Your rap and visual
some details about are too general, I
your person, but I could have made it
felt it was lacking up just by guessing
some specifics
about the person
and how they had
great ideas
Your rap and visual Your rap and visual
covered a few only covered one
major points about main idea.
your person
Reflection
4. I have learned that
.
5. I enjoyed most on
6. I want to learn more on
108
References:
Bentillo, Eulalia. 2012 Physics, Science and Technology. Quezon City, Philippines. FEP
Printing Corporation.
Campo, Pia. et.al. 2016. Science Learners Module. Pasig City, Philippines: FEP Printing
Corporation.
https://www.google.com/search
www.physicsclassroom.com
https://www.qoura.com/search
https://www.google.com/search?q=high+school+rubrics+for+poster&tbm=isch&ved=2ahU
KEwib_Y_Rm-_pAhULvJQKHZARBusQ2https://www.google.com/search?q=high+school+rubrics+for+video+presentation&tbm=isch
&ved=2ahUKEwib_Y_Rm_pAhULvJQKHZARBusQ2https://www.google.com/search?q=high+school+rubrics+for+a+rap+song&tbm=isch&ved=
2ahUKEwjx3u6bzunpAhVD3pQKHWyNBqIQ2cCegQIABAA&oq=high+school+ru
brics+for+a+rap+song&gs_lcp=CgNpbWcQAzoCCAA6BggAEAgQHlDDthRYkYUYL_xFGgBcAB4AIAB
109
Answer Key
Activity 1
I.
A
Series
B
Parallel
II. 1. No, because the flow of current is broken.
2. No, because the flow of current is broken.
3. Yes, because each bulb is individually connected to a voltage source.
4. Yes, because each bulb is individually connected to a voltage source.
5. Parallel, because even if one of the loads is broken, the rest of the loads will not be
affected.
Activity 2.
1. Yes. Because each appliance has its own path where current flows.
2. Yes. Because electrons or current follow different paths as they flow from negative to
positive terminal.
3. Yes. Because it does not affect the paths of the other appliances for current to flow.
4. No. Because all appliances connected in parallel operate with the same voltage source.
5. Parallel connection is preferred over series connection at home for reasons that all
appliances operate with the same voltage that is 220V and aside from that, if one of the
appliances will be damaged, the other appliances will still function. Unlike in series
connection, if one of the appliances will be damaged, the rest of the appliances will no
longer work or will no longer function.
Activity 3.
1. No. Because the flow of electrons or the flow of current is broken or cut.
2. If bulb c get busted, the rest of the circuit will no longer work.
3. No. Because in series connection, the voltage is shared in ratio to resistance. Hence,
the bulbs become dimmer.
4. If the stand fan is damaged, the entire circuit will not function anymore because the
path where current flows is disconnected.
5. No. The reason why homes aren’t connected in series is that, the voltage across each
appliance will be dropped and so, the last appliance will not get sufficient voltage to
drive current and if that happens, some of the appliances will not function well. Aside
from that, once you switched off the light during daytime, none of the appliances will
110
work. Subsequently, if lights are switched on during night time, the rest of the
appliances will also work and so, unnecessary energy is consumed.
Activity 4.
1. The main switch is connected in series with the rest of the loads or appliances at home.
2. Appliances like television, refrigerator, electric fans, electric pot, light bulbs and other
electrical appliances are connected in parallel.
3. No. Because the path for current to flow has been disconnected.
4. Yes. Because current can still flow or travel along a different path.
5.
Series Connection
Parallel Connection
Advantages
Current flows through every
component in the circuit. It is
useful when you need to
maintain a constant current
through
each
component
example in Christmas lights
All
loads
or
appliances
connected in the circuit gets
equal amount of voltage; it does
not affect the entire circuit even
if one of the loads is being
damaged and that current can
still pass through the circuit.
Disadvantages
If you are going to add more
output devices, the slower the
current becomes and once the
circuit is broken, the entire
circuit will no longer function
It requires a lot of wires in
connecting each appliance.
There could be a risk of fire in
some cases and increasing the
number of output devices does
not increase the resistance.
Prepared by:
DIANA D. LACAMBRA
Cataggaman National High School
111
SCIENCE 8
Name of Learner:
Grade Level:
Section:
Date:
LEARNING ACTIVITY SHEET
Electrical Safety Devices
Background Information for the Learners
Electricity is very essential. It provides us so many valuable things without which life
on earth would be difficult. It gives us light and enables us to enjoy some comfort. It also
facilitates the performance of certain tasks. But despite its many benefits, electricity could
bring danger like the most common house fires and electrocution, which is so fatal.
Electrical engineers or electricians often use safety equipment or devices to protect
the building as well as the people from injury due to electric shock in the human body.
Grounding wires protect people from shocks. If a short circuit occurs in a device,
current will go directly into the earth through a low resistance grounding wire. In this way a
person who touches the device will be protected. In order to protect people from shocks,
electrical systems are grounded. A circuit is electrically grounded when charges are able to
flow directly from the circuit into the ground connection in the event of a short circuit.
The following are some electrical safety devices (ESD) used in electric circuit that are found
in our homes and their functions.
1. Circuit breaker is a safety device that uses an electromagnet
that automatically shut off the circuit when there is an excess
current from overload or short circuit. It’s easy to reset the
circuit breaker. This is done by pulling back a switch after
turning off some of the appliances that are causing the high
current in the circuit.
circuit breaker
fuse
2. Fuse is a device that contains a thin strip of metal that
will melt if too much current flows through it. It protects
the load such as appliances from damaging effects of
overcurrent. When the strip of metal melts, or “blows”, it
breaks the circuit and stops the flow of current. The
electricity might have gone out because a fuse was
blown. Once the overload is corrected, the fuse can be
replaced and the electricity is restored. When a fuse
burns out, it cannot be used again.
112
3. Three-pronged plug. The two flat prongs connect the appliance
to the household circuit. This third prong, which is round,
connects the metal shell of an appliance to the ground wire of a
building. It serves as a ground conductor in order to protect
people from electrocution.
Plug with third prong
4. Lightning rod is a metal rod mounted on the roof of a
building in order to protect a building. It is also connected
to a grounding wire. When lightning strikes the rod,
charges flow through the rod, into the wire and then into
the Earth. This protects the building from lightning.
lightning rod
5. Double insulation protects the user of the appliance from
an electric shock by preventing any possibility of the
external casing becoming live thus, eliminating the need for
an earth connection. Some appliances have double
insulation, and only need live and neutral wires. They don’t
need an earth wire e.g. televisions, computers, printers, and
hairdryers.
Earthing
6. Earthing is the act of connecting the metal casing of
the appliance to earth via a wired connection to the
bare ground. Earthing wires usually have green and
yellow bands around them. It is also a method of
transmitting the instant electricity discharge directly to
the ground through lower resistance wires or electrical
cables. This is one of the significant features of
electrical networks. Because it builds the most eagerly
accessible and hazardous power source much secure to
utilize.
Learning Competency with Code:
Explain the functions of circuit breakers, fuses, earthing, double insulation and other
safety devices in the home. (S8FE-Ii-33)
113
Activity 1. Let’s Make Connection!
Directions: Match the devices in Column B and their respective functions in Column C with
the given pictures of items in Column A. Write your Coded answer in the space provided.
The first one is done for you.
Column A
Column B
Column C
Picture
Device name
Function
Column D
Coded answer
1.
A. Circuit
Breaker
I. Connects the metal shell of
an appliance to the ground
wire of a building
1. C, II
2.
B. Double
insulation
II. Transmits the instant
electricity discharge
directly to the ground
through lower resistance
wires or electrical cables
2.
3.
C. Earthing
III. Protects the building from
lighting discharge
3.
4.
D. Fuse
IV. Shuts off the circuit when
the current gets too high
using an electromagnet
4.
5.
E. Lightning
Rod
V. Protects the user of the
appliance from an electric
shock
5.
6.
F. Third Prong
VI. Melts if too much
current flows through it
6.
114
Activity 2. Can You Be My Partner?
Directions: Fill in the Venn diagram comparing circuit breaker and a fuse by transferring the
sentences below into their appropriate places.
Circuit breaker
Fuse
1.
2.
1.
1.
2.
2.
It looks like switches
Protects wiring from overheating
It contains a thin strip of metal
Uses electromagnet to shut off
It burns out and can’t be used again
Safety devices that break the circuit whenever overload or short occurs
115
Activity 3. Fact or Bluff?
Directions: Write FACT if the statement is correct and write BLUFF if the statement is
wrong and give the correct term in the underlined word to correct the statement. Write your
answer on the space provided.
1. The human body can be seriously injured by shocks, even those of less than one
ampere.
2. Wearing of rubber shoes or slippers when repairing electric appliances is one of the
safety measures in handling electricity.
3. Always plug an electrical appliance before attempting to open or repair it.
4. Never replace a blown fuse with coin or just any wire.
5. Never overload a circuit by attaching too
6. Always
replace
a
blown
fuse
with
a
many
coin
or
appliances
just
any
to
it.
wire.
7. Don’t ignore switches or outlets that don’t work. Have a qualified electrician check
the
outlets.
8. Don’t use old extension cords without inspecting them first.
9. Don’t switch on electric appliances with wet hands.
10. Pull on the plug, not on the cord to disconnect electrical appliance from the outlet.
Activity 4. Safety First!
Directions: Answer the following questions.
1. What are some important safety devices used in your own homes? Name at least 3 of
these electrical devices.
2. How should you prevent electric shock or electrocution?
3. What will happen to fuse if it burns out?
116
4. Why does connecting too many electrical appliances at the same time in one
extension wire with low quality often” blow “ or “burn” a fuse?
Reflection:
1. I learned that
2. I enjoyed most on
3. I want to learn more on
References and Link/s:
Acosta, Herma D.et.al. 2015. Science –Grade 10.Learner’s Material. Pasig City.
Department of
Education .
Bentillo, Eulalia N. et .al. 2004. Physics, Science and Technology Textbook for Fourth.
Quezon City. Department of Education .
Campo, Pia C., et. al. 2003. Science – Grade 8. Learner’s Module. Pasig City. Department
of Education.
Holt, Rinehart and Winston, Holt. 2001.Science and Technology, Physical Science. Austin,
Texas. A Harcourt Classroom Education Company. Austin, Texas.
Padilla, Michael J.et. al. 2001. Focus on Physical Science. Prentice Hall. New Jersey
Glenview, Illinois,
https://www.gcsescience.com/pe38.htm
https://www.thespruce.com/six-ways-of-prevent
117
Answer Key:
Activity 1.
118
1.
2.
3.
4.
5.
6.
C, II
E, III
B, V
A, IV
F, I
D, VI
Activity 2.
Circuit breaker
Fuse
1. It looks like switches
1. It contains a thin strip of
metal.
2. Uses electromagnet to
shut off
1. Protect wiring
from overheating
2. It burns out and can’t be used
again.
2. Safety devices
that break the circuit
whenever overload or short
occurs
Activity 3.
1.
2.
3.
4.
5.
Fact
Fact
Bluff , Unplug
Fact
Fact
6. Bluff, Never
7. Fact
8. Fact
9. Fact
10. Fact
Activity 4.
1. Answers vary (fuse ,circuit breaker, ground conductor ,prong)
2. Possible answers
a. Do not “flip”the circuit breaker as ON and OFF switch
b. Do not replace the burn fuse without putting down the main switch.
c. Never use a coin or piece of metal to replace a burn fuse.
d. Do not use old extension wires without inspecting them first.
e. Check the extension cord load limit.
f. Have a qualified or licensed electrician inspect the circuit breaker, fuse,
switches that don’t work anymore.
g. Unplug electrical appliances when not in use.
3. The color of the metal wire is black. If a fuse burns out no current will flow and all
lights and fixtures along the circuit go dead. It has to be replaced with new one.
4. If too many appliances are connected in a single extension cord this is overloading.
Overloading occurs when an electrical wires carries too much current. This may cause
the fuse wire to melt or burn because it exceeds the maximum current the household
wire can handle.
Prepared by:
VICTORIA T. IRINGAN
Cagayan National High School