An electric charge is a property of two bodies by virtue of which they are able to attract or repel each other. The electric charge can be positive or negative. The smallest or elementary charge carried by a proton or an electron. The charge carried by proton is said to positive and that by electron is said to be negative. Under ordinary conditions all bodies are electrically neutral because the positive charge on it is balanced by an equal amount of negative charge.
Nature of Charge
Rubbing the glass rod with the silk cloth and bringing the glass near small bits of paper. This shows that by rubbing or by friction a body gets energy and its presence is detected by the property of attracting light pieces. This form of energy is known as electricity.
Suspending a glass rod rubbed with silk cloth by means of dry silk thread and brings another glass rod rubbed with silk cloth near the suspended rod. It is found that the two glass rods repel each other.
Example Demonstrating the Nature of Electric Charge
Now take an ebonite rod and rub it with fur or car skin, this rod also develops the property of attracting bits of paper or it is also charged or electrified. Suspend such a rod by using a dry silk thread. Bring another ebonite rod rubbed with fur near the suspended rod and observe what happens is the rods repel. The charge developed on the ebonite rod when rubbed with fur is said to be the negative charge. This experiment also shows that two negatively charged rods repel each other. Now suspending a glass rod rubbed with silk by using a dry silk thread and brings an ebonite rod rubbed with fur near the suspended glass rod. It is found that the two rods attract each other. This experiment shows that a positively charged rod and a negatively charged rod attract each other.