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SCIENCE 7
QUARTER 3 MODULE 7 WEEK 7
CHARGES AND THE DIFFERENT CHARGING PROCESSES
Let’s Understand (Study the Concepts)
Nature of Charges and their Interaction
Electric charge is the physical property of matter that causes it to experience a force
when placed in an electromagnetic field. There are two types of electric charge: positive and
negative (commonly carried by protons and electrons respectively).
One
of
the
fundamental
laws
of
electricity
is
that
LIKE CHARGES REPEL, UNLIKE CHARGES ATTRACT. A positive charge and a negative
charge, being unlike, tend to move toward each other. In the atom, the negative electrons
are drawn toward the positive protons in the nucleus.
Atom- is the basic unit of matter that consists of a dense central nucleus surrounded
by a cloud of negatively charged electrons. It is made up of electrons, protons, and neutrons.
Electrons (-) - the subatomic particles that orbit the nucleus of an atom. They are
generally negative charge and are much smaller than the nucleus of the atom.
Protons (+) - are one of the most important types of subatomic particles Protons
combine with electrons and usually neutrons to make atoms.
Neutrons (0) - are subatomic particles contained in the atomic nucleus. They have
no net electric charge, unlike the proton’s electric charge.
Different Charging Processes
Charging means gaining or losing electrons. Charging objects can be done by
friction, conduction, and induction.
• Charging by Friction - is done by rubbing two materials together. In this method,
the electrons are transferred between the two objects which are rubbed. When a
glass rod is rubbed with a silk cloth, glass acquires a positive charge and silk
cloth acquires a negative charge. When an ebonite rod is rubbed with fur cloth,
an ebonite rod acquires a negative charge and fur cloth acquires a positive
charge.
• Charging by Conduction - or charging by contact involves physical touch
between a charged object and a neutral object. Some examples are: Touching a
stove and being burned, ice cooling down your hand, and boiling water by
thrusting a red-hot piece of iron into it.
• Charging by Induction – is a method of charging a neutral object without
physical contact. When we place the phone on the charging dock, an
electromagnetic field is produced between the induction coils. Once the
electromagnetic field is produced, electricity can pass through the two induction
coils, charging the phone wirelessly.
The Law of Conservation of Charge
Charges cannot be created nor destroyed but can be transferred from one material to
another. The total charge in a system must remain constant.
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The Triboelectric Series
The Triboelectric Series is a list that ranks materials according to their tendency to
gain or lose electrons. An atom can lose or gain electrons. When the atoms of the material
lose electrons, the material becomes positively charged. When the atoms of the material
gain electrons, the material becomes negatively charged.
What is positively charged?
If an object has more protons than electrons, it is positively charged. The number of
protons is more than the number of electrons in an element which gives the element its
positive charge as the protons.
What is negatively charged?
If an object has more electrons than protons, it is negatively charged. Physically, it
maintains the inverse reaction to positively charged particles, creating an electromagnetic
field that demonstrates a certain level of force, keeping both particles in a united and
reactive state.
The Importance of Grounding or Earthing
Grounding is the process of removing the excess charges in an object by means of
transferring electrons between it, and another object of a substantial size. It is also known as
Earthing. When a charged object is grounded, the excess charges are balanced by the
transfer of electrons between the charged object and the ground.
Importance of grounding
• Has a low chance of experiencing electrical overload which is a usual cause of
electricity-related accidents.
• Reduces the risk of frying appliances and equipment beyond repair, occurrence of
fire, and any physical injuries.
• It makes it easier for power to be directed straight to where it is needed in your
household.
• It allows the electrical current safely and efficiently travel throughout your home’s
electrical system.
Let’s Analyze
A. DIRECTIONS: Complete the table below, based on what you had read on the nature
of charge and the interaction of charges.
CHARGES
Positive
Negative
CHARGES
Negative
Positive
INTERACTION
Attract
Repel
B. DIRECTIONS: Identify the charging processes in the following situations: Write if
Friction, Conduction, or Induction.
_________________ 1. Charging a mobile phone
_________________ 2. Using a cloth to rub a plastic ruler
_________________ 3. Rubbing a balloon on your hair
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_________________ 4. Ice cooling down your hand
_________________ 5. Rubbing ebonite rod with fur cloth
C. DIRECTIONS: Study the use of the Triboelectric Series.
Find the two items. The one that is higher will become POSITIVE. The one that is
lower will become NEGATIVE. The farther apart the items are, the stronger the charging.
What will be the charge on each of the following materials if they are rubbed
together? Refer to the triboelectric series. Fill in the table below. (See Figure 3Triboelectric Series Comic strip on Science 7 Learner’s Material p.267)
SUBSTANCE
High affinity for capturing Electrons
(tendency to acquire a negative
charge) (-)
Give up Electrons (tendency to
acquire a positive charge) (+)
TENDENCY
Skin
(+)
Glass
Materials Rubbed
Together
1. hair & paper
Hair
Paper
Steel
Wood
Rubber
Copper
Polyester
Vinyl
PVC
(-)
Material
which
would Lose
Electrons
Charge of the
material after
Losing
Electrons
Material
which
would Gain
Electrons
Charge of the
material after
Gaining
Electrons
Paper
Positive
Hair
Negative
2. glass & copper
3. steel & copper
4. hair & polyester
5. rubber & skin
6. vinyl & wood
D. DIRECTIONS: Word Cryptogram: Unscramble the letters by placing the correct letter
inside the boxes.
1. The material used to ground a system.
4. Another term for grounding.
A
L
T
M
E
T
H
I
N
G
E
A
R
5. This may be connected to the
ground
for several reasons.
C I
R S T I
C U
2. The process of removing excess charges.
D I
N G N O G R U
3. One of the results of not using a grounding
system.
L O D A O V R E
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Let’s Try (Evaluation)
Multiple Choice: Select the letter of the correct answer. Write your answer on a separate
sheet of paper.
1. If you comb your hair and the comb becomes positively charged, then your hair
becomes ____ charged.
A. Positively
C. Uncharged
B. Negatively
D. Positive or negative
2. Which of the following materials will most likely be negatively charged by friction?
A. Human skin
C. Nylon
B. Teflon
D. Silk
3. Which of the following can be attracted by a positively charged object?
A. positively charged object
C. A neutral object
B. negatively charged object
D. No other object
4. A neutral metal sphere is touched by a positively charged metal rod. During the
process, electrons are transferred from the ____ to the ____ and the sphere acquires
a _____ charge.
A. sphere, rod, negative
C. rod, sphere, negative
B. sphere, rod, positive
D. rod, sphere, positive
5. Which of the following electronic devices is used in the field of medicine?
A. Ultrasound
C. Electrocardiograph
B. Magnetic resonance imaging
D. All of these
Let’s Create
CHARGE IT TO EXPERIENCE
DIRECTIONS: Draw a simple house electrical plan. Indicate the following by using symbols
or legends: Socket, Double socket, Switch socket, and Main control.
Standards: Your out-put will be evaluated based on the given RUBRICS
Criteria
Excellent
4
Very
Satisfactory
3
Satisfactory
2
Poor
1
How well
directions are
followed
All directions
were followed
Most directions
were followed
Some
directions
were followed
None of the
directions
were
followed
Use of creativity
Used own ideas
of the concept
Evidence of
some ideas
Evidence of effort
Took time & work
on the task w/ full
understanding
Significant
answers with
better
understanding
Answers are
acceptable but
lacks the idea
Answers made
with less effort
and
understanding
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Did not use
own ideas
Rushed
through and
did not work
hard