a) What do you observe? b) Is there any effect on the first refill in the tumbler? Do they attract each other or repel each other?

Question

Understanding types of charges: Inflate two balloons and hang them in such a way that they do not touch each other. Rub both the balloons with woollen cloth and release them.

a) What do you observe?

b) Is there any effect on the first refill in the tumbler? Do they attract each other or repel each other?

c) Now take a rubbed balloon near the rubbed refill in the tumbler and check the action. Do they attract each other or repel each other.

d) What can we conclude from these observations?

e) Does the repulsion between charged balloons indicate that they possess similar charge?

g) Does this activity remind you some of experiments that you have done in “Playing with Magnets” Chapter of class VI?

Answer 1

a) They repel each other. Take a refill and rub it with a polythene sheet. Keep it gently in a plastic tumbler. Take another refill and also rub it with the same polythene sheet.

Bring the second refill near the first one in the tumbler. Take care that you do not touch either of the rubbed portions on the refill with your hand.

b) Yes, there is effect on the refill in the tumbler. They repel each other.

c) They attract each other. In the first two parts of the above activity, two objects that were made of the same material have brought near to each other after being rubbed with some appropriate material.

In the third part, objects made of different materials were brought near to each other after being rubbed with some material.

Let us summarise our observations carefully.

1. A balloon rubbed with woollen cloth repelled another balloon of the same type. 

2. A refill rubbed with polythene repelled another refill rubbed with similar material. 

3. A ballon rubbed with woollen cloth attracted by a refill rubbed with polythene sheet.

d) Some charged objects are attracted and some charged objects are repelled with each other.

e) Yes, they possess similar charge.

f) Yes, they possess different charges.

g) Yes, we know that magnets attract objects made up of magnetic materials like iron, nickel, cobalt, etc. We also know that unlike poles magnet attract each other and like poles repel each other.