Chapter 20.1, Problem 2SSC

To determine

The reason that the comb lose its ability after a few minutes.

Answer to Problem 2SSC

The comb loses the charges it gained from the wool and becomes neutral once again.

Explanation of Solution

Introduction:

When two neutral objects are rubbed with each other, then transfer of charges between them occur due to which one object gains positive charge while the other gains negative charge.

Now, when a comb is rubbed with wool, then the comb gains negative charge leaving the wool positively charged. When this charged comb is brought near the small pieces of paper, then the pieces get attracted to the comb. But, after sometime the comb loses its extra gained negative charges to the surroundings due to which it loses its special ability of attracting the small pieces of paper.

Conclusion:

Due to the loss of extra charges, gained from the wool, to the surroundings, comb loses its ability to attract the small pieces of paper.