ELECTRIC CHARGE OF ITS NATURE

It is a common experience that a comb, after running through dry hair a few times, can attracts small dust particles or small pieces of paper. Similarly if we rub our hands on silk vest it would also attract small pieces of paper of dust particles, feather etc. When we take off acrylic sweater in a dark room we can see the sparks flying. All these observation demonstrate charging of friction.

To study the nature of charge closely let us take a glass rod, rub it with silk clothes and hang it freely by a silk thread. Let us take another glass rod and rub it with silk cloth as in the first case and take it towards the first rod. The suspended rod will swing away. This means that the two charged ends repel one another.

In the next experiment, take a glass rod, rub it with silk and suspended it as before. Take a hard rubber rod, rub it with woolen clothes and bring it near to the suspended glass rod. It is observed that they attract each other.

Here the charges on the glass rod are same in nature because both the glass rod were rubbed with the same material-silk. It is seen that, when brought closer, they repel. So, we conclude that similar charges repel. Charges developed on the rubber rod behave differently- they attracts the glass rod. Therefore, we conclude that charges on the glass rod are different in nature that on the rubber. Also unlike charges attract.

To investigate it further, take a rubber rod, rub it with the woolen cloth and hang it by a silk thread. Bring another rubber rod, rubbed with woolen clothes, near to the suspended rod will be repelled.

This type of experimental has been done with different set of materials. They revel that two different kinds of electrical charges are produced. Two bodies carrying the same kind of electrical charge repel one another. On the other hand two bodies carrying different type of electrical charge attract one another. Thus we conclude that charges repel; unlike charge attract.