Uploaded by Anne Marie Claire L. Medrano

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General
Physics 2
12
Quarter 3
Self-Learning Module 2
Electric Charge
For the Learner:
Welcome to the General Physics 1 Self-Learning Module on Electric Charge!
This module was designed to provide you with fun and meaningful opportunities
for guided and independent learning at your own pace and time. You will be enabled to
process the contents of the learning material while being an active learner.
This module has the following parts and corresponding icons:
Expectations - This points to the set of knowledge and skills
that you will learn after completing the module.
Pretest - This measures your prior knowledge about the lesson
at hand.
Recap - This part of the module provides a review of concepts
and skills that you already know about a previous lesson.
Lesson - This section discusses the topic in the module.
Activities - This is a set of activities that you need to perform.
Wrap-Up - This section summarizes the concepts and
application of the lesson.
Valuing - This part integrates a desirable moral value in the
lesson.
Posttest - This measures how much you have learned from the
entire module.
EXPECTATIONS
The module is about electric charge and its properties.
After going through this module, you are expected to:
1. describe charging by rubbing and charging by induction using ray
diagram;
2. explain the role of electron transfer in electrostatic charging by rubbing;
and
3. describe experiments to show electrostatic charging by induction.
PRETEST
Choose the letter of the BEST correct answer. Write the chosen letter in your
notebook.
1. Two balls are repelling each other as they hang from the ceiling. What
can you say about their charges?
A. one is positive, the other one is negative
B. both are positive
C. both are negative
D. both are positive or both are negative
2. A metal ball hangs from the ceiling by an insulating thread. The ball is
attracted to a positive-charged rod heald near the ball. What must be the
charge of the ball?
A. positive
B. negative
C. neutral
D. positive or negative
3. In which way is the electric force similar to the gravitational force?
A. Electric force is proportional to the mass of the object.
B. Electric force is similar in strength to gravitational force.
C. Electric force is both attractive and repulsive.
D. Electric force decreases in strength as the distance between the charges
increases
4. Which activity does not produce the same results as the other three?
A. sliding over a plastic-covers automobile seat
B. walking across a woolen carpet
C. scraping food from a metal bowl with a metal spoon
D. brushing dry hair with a plastic comb
5. A negatively charged object is brought close to the surface of a conductor,
whose opposite side is then grounded. What is this process of charging called?
A. charging by contact
B. charging by induction
C. charging by conduction
D. charging by polarization
RECAP
Atoms make up a matter consists of
subatomic particles. Give some important
details about these particles by completing
the table below:
-
Value of
charge
Coulomb (C)
-1.6 x 10 -19 C
Mass in
kilogram
(kg)
9.11 x 10 -31 kg
p
+
+1.6 x 10 -19 C
1.67 x 10 -27 kg
n
neutral
0
1.67 x 10 -27 kg
Name of
Particle
Symbol
Charge
Electron
e
Proton
Neutron
LESSON
Pairs of electrical charges have a force that acts between them. It is called the
electric force. Unlike gravity which can only be an attractive force, the electric force can
be either attractive or repulsive.
Electrostatics deals with the interaction of electric charge at rest. But how do
charges interact?
Have you ever experience something in the parts of your body that you can’t
explain where it came from? Like...
Copyright © https://google/images
receiving an electric
shock while touching a
doorknob?
Copyright © https://google/images
Copyright © https://google/images
your hair following the
movement of the balloon?
or spark between you
and your friend?
These are examples of how charges transfer from one object to another.
How do you think these objects acquire charges?
How do we know the charge of an object?
How does it transfer from one object to another?
Try rubbing a balloon with a piece of cloth and
place it near running water on your faucet...
What do you observe?
The water bends as the rubbed balloon moves
closer to it
Why do you think it happened?
The process of supplying the electric charge to an object or losing an electric
charge from an object is called charging. Electric charge is conserved. It can be
transferred from one object to another by moving electrons but it can not be
created nor destroyed.
On your browser, copy this link to explore how charges transfer from one
object to another https://phet.colorado.edu/sims/html/balloons-and-staticelectricity/latest/balloons-and-static-electricity_en.html
As you can see, the balloon, the cloth, and the wall are neutrally charged,
meaning they have equal numbers of protons and electrons.
When you rub
the balloon on the cloth,
the negatively charged
particles in the cloth are
being attracted to the
balloon.
Making the cloth positively
charged and the balloon
negatively charged. The cloth
becomes positively charged
because it has a deficiency in
electrons after rubbing. While
the balloon becomes negatively
charged because it has excess
electrons.
 Positive charge:
When an object has a positive charge, it means that it has more protons than
electrons.
 Negative charge:
When an object has a negative charge, it means that it has more electrons than
protons.
 Neutral charge:
When an object has an equal number of protons and electrons it means the object
is neutrally charged.
When you
release the negatively
charged balloon, it is
being attracted to the
positively charged
cloth. But if you place
the balloon near the
wall, you can see that
the negatively charged
particles on the wall
are being repelled by
the negatively charged
balloon. Thus we can
say that unlike
charges attract and
like charges repel
The law for electrostatic charge
simply tells us that as charges repel and
unlike charges attract.
Process of Charging:
 Charging by Friction
When two objects are rubbed against each other, charge transfer
takes place. One of the objects loses electrons while the other object
gains electrons. The object that loses electrons becomes positively
charged and the object that gains electrons becomes negatively
charged. Both the objects get charged due to friction and this method
of charging is commonly known as electrification by friction.
 Charging by Conduction
The method of charging an uncharged object by bringing it close and
in contact with a charged object is known as charging by conduction.
The charged conductor has an unequal number of protons and
electrons, hence when an uncharged conductor is brought near it, it
discharges electrons to stabilize itself.
A conductor is an object or type of
material that allows the flow of charge
(electrical current) in one or more
directions. Materials made of metal are
common electrical conductors.
Electrical current is generated by the
flow of negatively charged electrons,
positively charged holes, and positive
or negative ions in some cases.
 Charging by Induction
The process of charging an uncharged conductor by bringing it near a
charged conductor without any physical contact is known as charging
by induction.
An electrical insulator is a material
in which the electron does not flow
freely or the atom of the insulator
has tightly bound electrons whose
internal electric charges do not flow
freely; very little electric current will
flow through it under the influence
of an electric field.
Some examples of conductors and insulators:
https://www.toppr.com/ask/content/concept/classification-of-materials-conductors-and-insulators-209361/
ACTIVITIES
Activity 1 – Determining Charge
Determine the charge on the object and explain why it has this charge:
Reference: https://studylib.net/doc/8476708/01.1-laws-of-electric-charge-worksheet
Activity 2 – Law of Charges
Describe what charge is on each object and the law of electric charge is applied.
Reference: https://studylib.net/doc/8476708/01.1-laws-of-electric-charge-worksheet
WRAP-UP
Complete the table about what you have learned about electric charge:
VALUING/APPLICATION
EARTHING AND ITS ADVANTAGES:
Connecting a charged object to the earth
with the help of conducting wires or physical
contact is called Earthing. The earth is considered
to be a huge reservoir of electrons. Depending
upon the charge on the object, the earth provides
or accepts electrons from a charged object
connected to it.
Can you name some electrical appliances
at home that needs to be grounded or Earthed?
Reference:
https://www.toppr.com/ask/content/concept/classification-ofmaterials-conductors-and-insulators-209361/
POSTTEST
Choose the letter of the best answer. Write the chosen letter in your notebook.
1. When two dissimilar materials contact each other some of the electrons
in one material will be drawn into the other material, this effect can be
increased by rubbing the two surfaces together. What charging process is
involved?
A. charging by conduction
B. charging by friction
C. charging by induction
D. all of the above
2. A student has a neutrally charged glass rod and a neutrally charged silk
cloth. When the student rubs the silk cloth on the glass rod, the rod
acquires a net positive charge. What is the charge on the silk cloth after
the student performs this experiment?
A. the silk has no charge
B. the silk has a charge that is equal in magnitude to the glass rod’s
charge, but it is negative
C. the silk is positively charged and has a greater magnitude of charge
than the glass rod
D. the silk is negatively charged and has a smaller magnitude of charge
than the glass rod
3. All matters are said to be neutral wherein the numbers of electron and protons are
equal so once charges it do not stay for a long time because of the following factors
except;
A. amount of charge gain
B. presence of polar molecules
C. type of charge
D. type of material
4. Rubber is a nonconducting material that is why it cannot easily conduct
heat and electricity. Which is the best explanation for this situation?.
A. it has excess electrons which are loosely bounded with its nuclei so it
can free to move
B. it has a deficiency in electrons which are tightly bounded with their
nuclei so it can not move freely
C. it has few electrons
D. it has no electrons
5. A negatively charged object is brought close to the surface of a conductor,
whose opposite side is then grounded. What kind of charge is left on the
conductor’s surface?
A. neutral
B. negative
C. positive
D. both positive and negative
REFERENCES
Physics a First Course Teacher Resource CD-Rom, 2005. CPO Science.
Tony Wayne. Physics Students Workbook. Creative Commons
Noncommercial 3.0 United States License.
Attribution-
Faughn, J. S.; Serway, R. A. Holts Physics, Teacher’s Edition Textbook, 2006. Pages
160-163.
Tom Strong. Honors Physics Review Notes. 2009. Mt. Lebanon High School
Tony Wayne. Physics Students Workbook. Creative Commons
Noncommercial 3.0 United States License.
Attribution-
Walker, James S., Physics, Fourth Edition. 2010. Lecture Outline, Chapter 7.
Pearson Education, Inc.
Acknowledgment:
This module was collaborated and created by the
Division of Pasig City.
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