Chapter 32, Problem 40A

Would it be necessary for a charged object to actually touch the leaves of an electroscope (see Question 39) for the leaves to diverge? Defend your answer.

To determine

To explain: Whether it is necessary for a charged object to touch the leaves to diverge.

Answer to Problem 40A

No, it is not necessary. Using charge induction, like charges develop in the leaves and both repel apart.

Explanation of Solution

Introduction:

When a charged object is placed near a conductor, then charges are induced in the conductor such as it acts as a dipole.

When a charged object is placed near a metal ball, then charges are induced in the metal ball. Due to charge induction, the metal ball becomes a dipole, in which positive and negative charges are set in the opposite direction. This process keeps going on till it reaches the gold leaves. When gold leaves are induced with charges then both leaves have similar charges on the surfaces which are in near contact.

Thus, it is not necessary to actually touch the gold leaves, to set them apart.

Conclusion:

Thus, due to charge induction, like charges repel each other and leaves set apart. It is not necessary to touch the gold leaves.