Describe with the help of a diagram an instrument which can be used to detect a charged body.

An Electroscope is an instrument which can be used to detect whether a body is charged or not. The following figure shows the simple Electroscope.

Construction: An electroscope has a brass rod passing through a tight fitting cork in a glass bottle. A pair of thin aluminum leaves is attached to the lower end of the brass rod. To protect the aluminum leaves from external electric charge the lower half of the bottle is lined with tin foil which is ‘earthed’ by connecting it to the table.

Working: When a charged rod is touched to the metal disc, the charge is transferred to the aluminum leaves and they diverge.