Question

How can you find the nature of charge on a body with the help of a gold-leaf electroscope?

Answer 1

Step1: Charging

1. There are two ways to find the nature of the charge - by touching or without touching.
2. First of all, we need to charge the electroscope.
3. Let us assume the electroscope is positively charged.
   

Step2: Method 1: By touching the body to the electroscope.

1. Bring the body in contact with the brass disc of the electroscope.
2. If the divergence between the leaves decreases, the charge on the body is opposite to the charge on the leaves, in this case, negative.
3. This is because the excess negative charge goes into the leaves through the brass disc and reduces the net positive charge on the leaves.
4. If the divergence between the gold leaves increases, the charge on the body is the same as that of the charge on the leaves, in this case, positive.

This is because the electrons from the disc go into the body to neutralize the positive charge. Due to this, the leaves get more positive charge, and thus the divergence increases.
Step3: Method 2: Without touching the body to the disc.
1. Bring the body near the brass disc of the electroscope.
2. If the divergence between the leaves decreases, the charge on the body is opposite to the charge on the leaves, in this case, negative.
This is because the excess negative charge attracts the positive charge on the leaves through the brass disc and reduces the net positive charge on the leaves.
3. If the divergence between the gold leaves increases, the charge on the body is the same as that of the charge on the leaves, in this case, positive.
4. This is because the electrons from the disc repel the positive charge on the leaves through the brass disc. Due to this, the leaves get a more positive charge, and thus the divergence increases.
By following the above two methods, we can find the nature of the charge on a body using a gold-leaf electroscope.