Question

(a) If an electroscope is charged by conduction using a glass rod rubbed with silk, what charge will be developed on the leaves of the electroscope?
(b) If the same glass rod is used to charge the electroscope by induction, what charge is developed on the leaves?
(c) If the charged electroscope is touched with a wooden rod, what happens?

Answer 1

(a) If an electroscope is charged by conduction using a glass rod rubbed with silk, a positive charge is developed on the leaves of the electroscope. A glass rod acquires a positive charge when it is rubbed with silk, and when it is made to touch an electroscope, electrons move from the electroscope rod to the glass rod, and the leaves of the electroscope acquire a positive charge and diverge.

(b) If the same glass rod is used to charge the electroscope by induction, then a positive charge is developed on the leaves of the electroscope. This is because the glass rod is positively charged, and so the near end of the electroscope rod acquires the opposite charge, i.e., negative charge, by the process of induction. However, the far end becomes positively charged, and the leaves of the electroscope diverge.

(c) If the charged electroscope is touched with a wooden rod, then no changes take place, because wood is an insulator.