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 gold leaves is attached to the lower end of the brass rod. To protect the gold leaves from an 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 gold leaves and they diverge.