ACTIVITY SHEET
ACTIVITY SHEET
Learning Activity Sheets (LAS)
Republic of the Philippines
Department of Education
Region III
School Division Office of Bulacan
CARLOS F. GONZALES HIGH SCHOOL
Name of Learner: __________________________ Grade and Section:________
Date: ______________
Maguinao, San Rafael, Bulacan
GENERAL PHYSICS 2 ACTIVITY SHEET
Electric Charge
LEARNING ACTIVITY SHEET 1 in
Learning Competency with Codes
Describe using a diagram charging by rubbing and charging by induction
(STEM_GP12EMIIIa-1).
Explain the role of electron transfer in electrostatic charging by rubbing
(STEM_GP12EMIIIa-2).
Describe experiments to show electrostatic charging by induction
(STEM_GP12EMIIIa-3).
GENERAL PHYSICS 2
(First Quarter)
“Electric Charges”
NAME:_______________________________________________
GRADE AND SECTION: ______________________________
DATE OF SUBMISSION: _____________________________
CFGHS-GP-G12- __________
1
Background Information for Learners
CHARGE INTERACTIONS
We can hardly deny the fact that electricity has been an important part of our
lives --- everywhere we look there is electricity! Electricity is present when your feet
scuff across the rug; do not be surprised by the crackles and sparks that you can hear
and feel as you comb your hair on a dry day, because that is just electricity at work; and
don’t dare to go out during a lightning strike because it’s definitely an enormous discharge of static electricity. On a greater extent, and literally speaking, electricity keeps
the world intact. Of course we cannot neglect gravity’s influence, but the main reasons
why molecules in your body stick together are the electric forces.
All the above-mentioned phenomena can be explained by electrostatics which is
the study of electricity at rest. Electrostatics includes the concepts of electric charges,
the forces between them, and their behaviors in materials. What is referred to as at rest
in electrostatics is the body that carries electrons which are the prime movers of electricity. The negatively charged electrons are in endless motion in matter and affect the
behavior of matter through electric charge.
ELECTRICAL CHARGES AND FORCES, AND MATTER
To have a first-hand experience of electrostatics, get a piece of paper and make
tiny bits out of it. Then, get your pen and rub it against your shirt. After doing so, place
your pen near the tiny bits of paper and observe what happens. Do you know the reason behind what you have observed? Well, it is just electrostatics at work!
As you rub your pen against your shirt, the pen becomes a charged object,
hence, it exerted a strange influence upon the tiny bits of paper. This influence known
as the electric force caused the pen to attract the tiny bits of paper, which are still neutral. This electric force is an example of a non-contact force which means that it will still
be present even when the charged pen will be placed at some distance away from the
bits of paper. Moreover, this electric force can be exerted by a charged object upon other objects --- may they be charge or uncharged (neutral)
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The electric force comes from particles in atoms. Refer to Figure 1. Based on the figure as well as based
on what you have learned from your previous science
classes, the following are the salient information
about atoms:
Each atom has a positively charged nucleus
containing protons and neutrons.
Protons are positively charged particles, while
neutrons are uncharged particles.
The electrons which are the negatively charged
particles, orbit around the nucleus.
Atoms are normally electrically neutral (zero net
charge) for they have equal number of pro- Figure 1. The Structure of Atom (Retrieved
tons and electrons.
from
https://www.ck12.org/book/ck-12The positively charged protons attract the negatively charged electrons which the
reason why the electrons are held in their orbits. On the contrary, electrons repel other
electrons. Remember, “Opposites attract. Likes repel.” The attractive and repulsive
force is attributed to a property known as charge. There are two types of charge --negative and positive --- that exist in all materials and in all states of matter. These
charges arise from electron and proton, respectively. In your activity earlier, the charge
acquired by the pen when it is rubbed against your shirt is positive, since it lost its electrons. While the charge acquired by your shirt which has greater electron affinity, is negative since it gained electrons.
TRANSFER OF ELECTRIC CHARGE
As mentioned earlier, atoms are normally neutral. However, by means of different
charging processes which can add or remove electrons, a material can be given a net
charge. Electrons transfer from one atom to another, but protons do not. Electrons
which are on the outer part of the atom are easy to add or remove as compared with
protons. Adding or moving protons requires nuclear reactions. Thus, the charge of an
object is brought about by the transfer of electrons. This means that, when an object is
negatively charged it has gained electrons --- more electrons than protons. On other
hand, a positively charged object has lost its electrons, thereby, it contains more protons than electrons.
Electric charges also follow conservation law. The law of conservation of
charge states that the net charge of an isolated system remains constant. This is because charge is neither created nor destroyed, it can only be transferred from one system to another. There are different ways for an object to become charge. For this lesson, we will focus more on charging by rubbing and induction.
.
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What do you usually observation
after brushing a plastic comb
through your hair during a dry day?
Isn’t it that the strands of your hair
are attracted to the comb? This is
the result of rubbing which makes
your hair and the plastic comb electrically charged. Charging by rubbing or friction is the most common
type of charging. But how does this
Figure 2. (a) Initially, the comb and the hair are neutral. (b) After really happen?
rubbing, the comb becomes negatively charged, while the hair Rubbing two different materials
becomes positively charged. (Retrieved from https:// having a different pull on their outer
electrons, will cause the electrons
to transfer between these materials. This will then result to an imbalance in the number
of electrons and protons, which makes the objects electrically charged. For instance, in
the case of your hair and the comb, electrons jump from your hair to the comb. Thus,
your hair becomes positively charged and the comb having more electrons, negatively
charged. But don’t forget the law of conservation of charge --- the net charge of the
comb-hair system is still zero (or it remains constant).
Charging by friction or rubbing is also referred to as triboelectric charging process. We know that an object is made up of different atoms, and the presence of different atoms affect the electrical properties of objects. One of these properties known as
electron affinity, plays an important role in triboelectric charging. Technically speaking,
electron affinity refers to the quantity of energy released upon the addition of electron to
a neutral atom or molecule to form a negative ion. Let’s make an analogy to make
things simple. Electron affinity is a property that refers to the relative amount of admiration that a material has for electrons. A high electron affinity therefore means that a material has relatively high admiration for electrons.
As shown in Figure 2, after rubbing, the comb becomes negatively charged. This
gives us an idea that the comb has higher electron affinity than the hair. The higher
electron affinity of the comb enables its atoms to pull the electrons from the hair, leaving
both objects electrically charged.
CHARGING BY INDUCTION
Even when there is no actual or physical contact between objects, charging can
still take place. Charging by means of induction happens when a charged object is
placed near a conducting (neutral) surface. During induction, the electrons move to one
part of an object by the electric field of another object. This charging process induces
an opposite type of charge. This means that the charged object does not lose its
charge, instead, the charges simply pile up --- negative charge on one side and positive
charges on the other side.
To fully understand the process of induction, you must also understand the nature of conductor as well as the process of polarization. The following are the important
concepts about conductors:
Conductors allow charges to move freely through them.
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Figure 3. Charging a two-Sphere system using a negatively charged object. (Retrieved from https://
Metals are good conductors. They have many free electrons that
can move about the material.
When we speak of polarization, we are talking about a process of
separating opposite charges within an object.
The figure below illustrates how a charge is induced in an object.
Based on Figure 3, the following can be deduced:
•
•
•
•
•
•
Initially, the two metal spheres placed side by side and mounted on
insulating stands are neutral in charge. Since these spheres are
conductors (they are made of metals), electrons can therefore freely
move between them.
When the negatively charged rubber balloon was placed near the
spheres (as shown in Diagram ii), the negative charges in the twosphere system were induced to move away from the balloon. The
negative charges in the balloon repelled the negative charges in the
spheres. Meanwhile, the positive charges on sphere A are attracted
by the negatively charged balloon.
Since the negative charges are in a conductor, they can freely
move about the surface. Most of the negative charges moved from
sphere A to sphere B.
The movement of electrons caused the two-sphere system to be
polarized. Hence, the spheres become electrically charged. Sphere
A is now positively charged since certain number of electrons
moved to sphere B. Sphere B now becomes negatively charged.
When the spheres are separated (as shown in Diagram iii), each
one is charged, and they have opposite charges.
When the negatively charged balloon was removed, the excess
charges on the two-sphere system become uniformly distributed.
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Pre-Test
Directions: Choose the letter of the correct answer. Write your answer on a separate
sheet of paper.
1. What is the attraction or repulsion between electric charges?
a. electric field
b. electric force
c. friction
d. conduction
2. The region around a charged object where the object’s electric force interacts with
other charged objects.
a. electric field
b. electric force
c. friction
d. conduction
3. A buildup of charges on an object.
a. friction
b. conduction
c. induction
d. static electricity
4. The law that states that charges are neither created nor destroyed but only transferred from one material to another.
a. friction
b. conduction
c. conservation of energy
d. static electricity
5. A method of charging an object by rubbing it against another object.
a. friction
b. conduction
c. induction
d. static electricity
6. A method of charging an object by allowing electrons to flow by direct contact from
one object to another.
a. friction
b. conduction
c. induction
d. static electricity
7. A method of charging an object by means of the electric field of another object.
a. friction
b. conduction
c. induction
d. static discharge
8. The loss of static electricity as electric charges transfer from one object to another
a. friction
b. conduction
c. induction
d. static discharge
9. Charges that are the same ___________________ each other .
a. attract
b. repel
10. Charges that are different _________________ each other .
a. attract
b. repel
11. The property of material due to which it attracts or repels other objects is ______.
a. friction
b. velocity
c. current
d. charge
12. Which of the following sets of hypothetical observations about an object would
demonstrate the existence of a third kind of electric charge?
a. It repels positive and attracts negative charges.
b. It attracts positive and repels negative charges.
c. It attracts positive and negative charges.
d. It attracts positive and negative charges and repels itself.
13. Two identical electroscopes, one initially charged and the other initially neutral,
are connected by a thin rod. If both electroscopes are now charged, you can conclude that
a. the rod is a conductor.
c. the rod is an insulator.
b. they have opposite charges.
d. one electroscope is grounded.
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14. Two parallel plates have equal but opposite charges. The electric force on a negative charge placed near the center of the plates is
a. perpendicular to the plates and points toward the positive one.
b. perpendicular to the plates and points toward the negative one.
c. parallel to the plates.
d. zero.
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3. The figure below shows charging a two-sphere system using a
positively charged object. Explain how this process takes place
using the given figure. You may have your answers in bullet form.
15. 1. Which of the following can be used to charge a metal rod that is held in your
hand? Rub it with
a. fur.
b. silk.
c. wool.
d. It can't be done
Activity Proper
Exercises/ Activities
Exercise 1: Think and Critically
This time you will be showcasing your analytical as well as critical thinking
skills. Using your knowledge on charging process, analyze answer the following
questions:
1. The figure below shows two identical neutral metal
spheres touching each other. Which of the following
locations of a positively charged insulating rod will
create the largest positive
A
charge in sphere Y?
B
C – Rod is
X
Y
D
2. Refer to the figure below. Would the charges induced on spheres A and B necessarily be exactly equal and opposite?
The figure below shows charging a two-sphere system using a positively charged
object. Explain how this process takes place using the given figure. You may
have your answers in bullet form.
(Retrieved
from
https://www.physicsclassroom.com/class/estatics/Lesson-2/Charging-by-
7
(Retrieved
from
https://www.physicsclassroom.com/class/estatics/Lesson-2/Charging-by-
4. Consider the illustration on the
right. A lightweight, positively
charged ball and a neutral metal
rod hang by threads. They are
close but not touching. A positively charged rod is held close
to, but not touching, the hanging
rod on the opposite end of the
ball.
4.1. Draw a diagram of the final positions of the hanging rod and
the ball. Provide an explanation for your diagram.
4.2. Suppose the positively charged rod is replaced with a negatively charged rod. Draw a diagram of the final positions of
the hanging rod and the ball. Provide an explanation for your
diagram.
Exercise 2: Let’s Do Physics!
Hello, young physicist! You have been doing great so far, and it
seems that you are still up for more challenges! For now, you will be
performing simple experiments that will help you have a clearer understanding about the two charging processes --- rubbing and induction.
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Materials: comb, tiny bits of paper, water source (faucet), drawing
materials
Procedures:
1. Charge the comb by running it through your hair. This works well
when the weather is dry.
2. Place
the comb near the tiny bits of paper. Observe what
happens.
3. Repeat step 1.
4. This time place the charged comb near a thin stream of running
water from a faucet. Observe what happens.
Guide Questions
1. Draw and describe what you have observed when the charged
comb was placed near the tiny bits of paper.
2. Draw and describe what you have observed when the charged
comb was placed near a thin stream of running water from a faucet.
3. What type of charging process took place between:
the comb and your hair?
the charged comb and the tiny bits of paper?
the charged comb and a thin stream of running water from a faucet?
4. What is the role of electron transfer in the charging process that
took place between the comb and your hair?
5. Explain the following charging processes: (a) rubbing and (b) induction.
Reflection
Before you proceed to your next journey, you need to answer the
following important question:
So What?...What takeaways from the lesson will be important to
know three years from now? Why?
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Post-Test
Directions: Choose the letter of the correct answer. Write your answer on a separate
sheet of paper.
1. What is the attraction or repulsion between electric charges?
a. electric field
b. electric force
c. friction
d. conduction
2. The region around a charged object where the object’s electric force interacts with
other charged objects.
a. electric field
b. electric force
c. friction
d. conduction
3. A buildup of charges on an object.
a. friction
b. conduction
c. induction
d. static electricity
4. The law that states that charges are neither created nor destroyed but only transferred from one material to another.
a. friction
b. conduction
c. conservation of energy
d. static electricity
5. A method of charging an object by rubbing it against another object.
a. friction
b. conduction
c. induction
d. static electricity
6. A method of charging an object by allowing electrons to flow by direct contact from
one object to another.
a. friction
b. conduction
c. induction
d. static electricity
7. A method of charging an object by means of the electric field of another object.
a. friction
b. conduction
c. induction
d. static discharge
8. The loss of static electricity as electric charges transfer from one object to another
a. friction
b. conduction
c. induction
d. static discharge
9. Charges that are the same ___________________ each other .
a. attract
b. repel
10. Charges that are different _________________ each other .
a. attract
b. repel
11. The property of material due to which it attracts or repels other objects is ______.
a. friction
b. velocity
c. current
d. charge
12. Which of the following sets of hypothetical observations about an object would
demonstrate the existence of a third kind of electric charge?
a. It repels positive and attracts negative charges.
b. It attracts positive and repels negative charges.
c. It attracts positive and negative charges.
d. It attracts positive and negative charges and repels itself.
13. Two identical electroscopes, one initially charged and the other initially neutral,
are connected by a thin rod. If both electroscopes are now charged, you can conclude that
a. the rod is a conductor.
c. the rod is an insulator.
:
9
b. they have opposite charges.
d. one electroscope is grounded.
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11
12
Exercise 1:
Rods A, B, and D will each polarize the spheres, drawing negative charges toward
themselves and leaving the opposite site positively charged. Thus, A will cause the
right sphere to be most positive. The actual or direct contact between the insulating
rod and spheres will cause some of the polarized negative charge from the
spheres to flow onto the rod. Since the rod is an insulator, this leaves the spheres
with only a small excess positive charge that will be shared between both spheres.
Because each single positive charge on sphere A is the result of a single electron being
taken from A and moved to B, the charge must therefore be equal and opposite on
both spheres. This is like taking bricks from the surface of a brick road and putting
them all on the sidewalk. The number of bricks on the sidewalk will be exactly
matched by the number of holes in the road. Similarly, the number of extra electrons on sphere B will exactly match the number of “holes” (positive charges) left in
sphere A. remember that the absence of an electron makes a positive charge.
b. silk.
c. wool.
d. It can't be done
Diagram i
Initially, the two metal spheres placed side by side and mounted on insulating
stands are neutral in charge.
Since these spheres are conductors (they are made of metals), electrons can
therefore freely move between them.
Diagram ii
When the positively charged rubber balloon was placed near the spheres, the negative charges in the two-sphere system were induced to move towards the balloon (opposite charges attract, like charges repel).
The positive charges in the balloon attracted the negative charges in the spheres.
Since the negative charges are in a conductor, they can freely move about the
surface. The negative charges on sphere B moved to sphere A.
Meanwhile, the positive charges on sphere A are repelled by the positively charged
balloon (They just lined up on one side of sphere A, far from the positively
charged balloon. Remember, protons do not move from one object to another).
The movement of electrons caused the two-sphere system to be polarized. Hence,
the spheres become electrically charged. Sphere A is now negatively charged
since certain number of electrons moved to sphere A. Sphere B now becomes
positively charged.
Diagram iii
When the spheres are separated each one is charged, and they have opposite
charges.
a. fur.
15. 1. Which of the following can be used to charge a metal rod that is held in your
hand? Rub it with
a. perpendicular to the plates and points toward the positive one.
b. perpendicular to the plates and points toward the negative one.
c. parallel to the plates.
d. zero.
14. Two parallel plates have equal but opposite charges. The electric force on a negative charge placed near the center of the plates is
Answer Key
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14
Exercise 2: (Guide Questions)
The diagram must look like the one presented below.
13
Exercise 1:
Diagram iv
When the negatively charged balloon was removed, the excess charges on the twosphere system become uniformly distributed.
4.1. The positive rod induces a charge in the hanging metal rod. The negative charges
in the hanging metal rod were attracted by the positively charged rod. On the other
hand, the positive charges in the hanging metal rod were repelled. Hence, they
lined up on the far opposite (right) end which caused the positively charged ball to
repel as well.
Retrieved from (https://byjus.com/physics/charge-transfer/)
When the charged comb was placed near the tiny bits of paper, the tiny bits of paper
moved towards the comb (they were attracted). The bits of paper are neutral in
charge (equal number of protons and electrons). When the negatively charged
comb is placed near them, their electrons move away from the electrons on the
comb. Simultaneously, their positive protons move towards the comb.
The diagram must look like the one presented below.
4.2. The negative rod induces a charge in the hanging metal rod. The positive charges
in the hanging metal rod were attracted by the negatively charged rod. On the other
hand, the negative charges in the hanging metal rod were repelled. Hence, they
lined up on the far opposite (right) end which caused the positively charged ball to
be attracted to the hanging metal rod.
Retrieved from (https://thebeakerlife.com/water-bending-experiment-13480a95eeda?
gi=41257b6e546)
When the charged comb was placed near a thin stream of running water from a faucet,
the water tends to bend. Water is neutral in charge (equal number of protons and
electrons). When the negatively charged comb is placed near the water, the
water’s electrons move away from the electrons on the comb. Simultaneously, the
water’s positive protons move towards the comb.
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15
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Tillery, B. W. Physical Science. Singapore: WCB McGraw Hill, 1999.
The Fact Factor. 2020. Wave Theory Of Light: Its Propositions, Merits And Demerits.
[online] Available at: <https://thefactfactor.com/facts/pure_science/physics/wavetheory-of-light/7662/> [Accessed 15 January 2021].
Silverio, A. A. Exploring Life Through Science: Physics. Quezon City: Phoenix Publishing House, Inc., 2007
Santisteban-Cook, C.J. Baguio, S.S. M. Breaking Through General Physics 2 for Senior
High School. Quezon City: C & E Publishing, Inc., 2018.
Physics
Classroom.
“Triboelectric
Charging.”
Available
at:
https://
www.physicsclassroom.com/class/estatics/Lesson-2/Charging-by-Friction
[Accessed 15 January 2021].
Physics
Classroom.
“Charging
by
Induction.”
Available
at:
www.chicagomanualofstyle.org/tools_citationguide/citation-guide-1.html
[Accessed 15 January 2021].
https://
Padua, A. L., and Crisostomo, R. M. Practical and Explorational Physics. Quezon City.
Vibal Publishing House, Inc., 2010
Hewitt, P. G. Conceptual Physics. Singapore: Pearson, Education, Inc., 2005.
Giancolli, D. C. Physics Principles with Applications. Philippines: Prentice Hall, 2007.
Cutnell, J. D. and Johnson, K. W. Introduction to Physics. Singapore: C & E Publishing,
Inc., 2010
Bord, D. J., and Ostdiek, V. J. The World of Physics. Manila: Vibal Publishing House,
Inc., 2012.
Exercise 2: (Guide Questions)
a. Charging by rubbing
b. Charging by induction
c. charging by induction
As mentioned in the previous item, the charging process that took place
between the comb and the hair is rubbing. Rubbing two different objects against each other causes electrons to transfer from one material to another. In this case, one object loses its electrons, while the
other object gains electrons. Hence, making the objects electrically
charged. The one with excess electrons is a negatively charged object, and the object having electron deficiency is a positively charged
object. Thus, the role of electron transfer in this case is to make initially neutral objects become electrically charged.
a. Charging by rubbing takes place between two objects that are in direct
contact with each other. Rubbing two different materials having a
different pull on their outer electrons, will cause the electrons to
transfer between these materials.
b. Charging by means of induction happens when a charged object is
placed near a conducting (neutral) surface. During induction, the
electrons move to one part of an object by the electric field of another object. This charging process induces an opposite type of
charge.
Pre-Test
1. B
2.A
3. D
4. C
5. A
6. B
7. C
8. D
9. B
10. A
11. D
12. D
13. A
14. A
15. D
Post-Test
1. B
2.A
3. D
4. C
5. A
6. B
7. C
8. D
9. B
10. A
11. D
12. D
13. A
14. A
15. D
References
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