Question

When an electroscope is charged, its two leaves repel each other and remain at an angle. What balances the electric force of repulsion so that the leaves don’t separate further?

Answer 1

The leaves of a charged electroscope separate due to electrostatic repulsion. This force has both a vertical and horizontal component, with the vertical component being balanced by the gravitational force. The leaves do not separate further because the electrostatic and gravitational forces are balanced.

Step-by-step explanation:

The leaves of a charged electroscope separate due to electrostatic repulsion. This force has both a vertical and horizontal component. The vertical component is balanced by the gravitational force, while the horizontal component causes the leaves to move apart.

For example, when a positively charged object is brought near the electroscope, it attracts negative charge to the top of the electroscope, leaving the leaves positively charged. These like charges repel each other, causing the leaves to separate, but they do not continue to separate further because the gravitational force and the electrostatic force are balanced.

Additionally, an electroscope can also be negatively charged by contact with a negatively charged object, inducing a charge on the leaves and causing them to separate.

Answer 2

There are two forces acting on the leaves. 1. Electrostatic force acting horizontally repelling one leaf from the other.
2. The force of gravity acting vertically downwards.
When each leaf is at 45 deg to the vertical the electrostatic force will equal the gravitational force on each leaf.