Lesson Planning of Electric Charge
Subject General Science
Students` Learning Outcomes
- After studying this lesson, students will be able to:
- Explain the production of electrical charges in some common materials.
- Explain the phenomena of lighting.
Science Processing Skills
Observing, Classifying, Communicating, Inferring, Predicting and Experimenting
Information for Teachers
- All materials are made of atoms that contain protons, electrons and neutrons. Protons have a positive charge and neutron have no charge.
- The protons and electrons are equal in number to an atom, therefore the net charge on an atom is zero. The protons and neutrons are strongly bound in the central part called the nucleus whereas electrons are loosely attached to the nucleus.
- When two objects are rubbed together, some electrons from one object move onto the other. Due to the gain of electrons, the number of electrons on one object exceeds the number of protons, so negative charge appears on it. Since the number of electrons left on the second object becomes less than the number of protons on it., positive charge appears on it.
The properties of the charges are:
- There is attraction between two oppositely charged objects.
- There is repulsion between two similarly charged objects.
Material / Resources
Writing board, chalk / marker, duster, two balloon, thread, stand and woolen cloth, a plastic comb,
- Ask the students, have they ever noticed that a plastic comb can attract tiny bits of paper after combing dry hair?
- Those who are with dry and have a plastic comb or plastic ball pen can try this activity right away. What causes this attraction?
- The students should discuss the matter and the teacher should write the key points on board. then proceed with activity 1.
- Divide the whole class into suitable groups and tell them to follow the given instruction:
1. Suspend an inflated balloon from the stand by means of a thread.
2. Bring a woolen cloth near it. Does the cloth attract the balloon towards it?
3. Now, rub the balloon vigorously with this cloth and take it away.
4. Then bring the cloth close to the balloon slowly. Does the cloth attract the balloon this time?
5. Why does the cloth attract the balloon after rubbing?
- 3. Wind up the discussion by writing on the board:
1. The charge is the basic property of matter.
2. It is of two types. One type is called positive and the other negative.
- 3. On rubbing two objects, one type of charge appears on one object and the other type on the second object.
4. The principle of charges is that opposite charges attract each other
- Divide the whole class into suitable groups and tell them to follow the given instructions:
1. Suspend two inflated balloons at some distance from one another.
2. Bring the balloon closer by moving the stands. Do they attract or repel each other?
3. Rub each balloon with a woolen cloth and bring them closer. Observe their movement. Do they repel or attract each other?
4. Now rub one balloon with a woolen cloth and the other with an object made of plastic. Bring them closer and observe their movement.
5. Do they attract or repel each other?
6. What do you think is the reason for this kind of action?
- Wrap up the discussion by explaining that, when both the balloons are rubbed with woolen cloth, same kind of charge comes on both of them, so they repel each other. When one balloon is rubbed with cloth and the other with plastic, both of them have opposite charges. As a result they attract each other. So, we conclude:
1. There are two kinds of charges.
2. Similar charges repel each other.
3. Opposite charges attract each other.
Why the charges appear on the objects on rubbing?
- We know that opposite charges attract each other and sometimes they produce a spark. The lightening in the clouds is also a spark. When water vapours rise up from the ground, they are charged due to friction of air. These vapours form charged clouds. When oppositely charged clouds come close to each other, a big spark is produced in the form of lightening. It is also known as static electricity.
Material / Required
Plastic comb, woolen cloth, an iron nail or a key
- For this activity a dark room or a corner is preferable. Divide the whole class into suitable groups and tell them to follow the given instructions:
1. Charge the plastic comb by rubbing it with a woolen cloth.
2. Touch it gently to a metallic key.
3. Observe carefully while touching. What did you see?
- Guide the student that a little spark is seen. When charged comb is brought closer to the key, opposite charge appears on near part of the key. The touch of the oppositely charged bodies produce spark. We conclude that:
- Spark is produced when two oppositely charged objects touch each other.
- If the opposite charges are in large quantities, a very big spark is produced such as lightening.
Sum up / Conclusion
- Electric Charge is a force possessed by a subatomic particle, be it a proton, neutron or electron, and which influences another proton, neutron or electron, either by attracting or repelling it. The electrons are rotating around the nucleus and have a negative electrical charge (-). …
- Static electricity is also known as static energy.
- A phenomenon of accumulation of an excess of electrical charge that occurs when the electrical charges of certain atoms decompensate and stop being neutral, which is their usual state.
1. Mark (√) for true sentence and (X) for false one.
i. Net charge on an atom is zero.
ii. Electrons carry positive charge
iii. Similar charges repel each other
2. Match column (A) with column (B)
3. Circle the correct answer from the following:
Two opposite charges:
i. Attract each other
ii. Repel each other
iii. Heat each other
iv. Have no effect on each other
4. How can an inflated balloon be charged negatively?
5. How can an inflated balloon be charged positively?
6. Why does positive or negative charge appear on the objects on rubbing?
7. Explain the phenomena of lightening.
. Follow up