describe an experiment to show that there are two kinds of charges.

1. Take a glass rod and rub it with silk. Suspend this freely from a silk thread. Take another glass rod rubbed with silk. Bring both the charged glass rod together. Observe that the suspended charged rod shows repulsion.
2. Take a glass rod and rub it with silk. Suspend it freely by a silk thread. Take an ebonite rod and rub it with cat’s skin. Observe that the glass rod is attracted by the ebonite rod. Observe that the suspended charged  rod shows attraction.

The charge produced on the glass rod is called positive charge; whereas the charge produced on the ebonite rod is called negative charge. Hence there are two kinds of electric charges namely positive and negative.