Things Required:
Balloon
A piece of wool or felt
Directions:
Inflate a balloon and stroke it with a piece of wool or felt. If you don’t have any fabric material, you can stroke the balloon against your hair. Place the balloon against the wall. What happens? How long will the balloon cling to the wall? Recharge the balloon and observe how well it clings to other objects, such as wood, a metal cabinet and glass.
This Is What Happens:
As the balloon is rubbed with wool, it becomes negatively charged. This charge produces an invisible electric field.
When the balloon is brought close to the wall, the negative charges in the wall are repelled by the negative field of the balloon. These charges move deeper (migrate) into the wall. As they leave the wall region nearest the balloon, they create a positive wall surface. As a result, the positive wall and the negative balloon attract.
The wall became charged by induction. In this type of charging, objects don’t touch. Instead, an electric field causes charges to migrate in surrounding materials. Although the number of charges remain the same yet they are unequally distributed. Regions with more positive charges take on a net positive charge. Regions with more negative charges take on a net negative charge.
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