Chapter 20, Problem 29A

To determine

To explain: The reason for attracting a dust by a CD that is wiped with a clean cloth.

Explanation of Solution

Introduction:

Insulating materials becomes charged by rubbing against each other. This is called charging by friction. While rubbing, the electrons (that are negatively charged)will be rubbed off from one material and move in to another material. The material which lost its electrons becomes positively charged and the material which gains electrons becomes negatively charged.

Rubbing the compact disk with a cloth charges it by friction. It may be positive or negative. Any charged material attracts the neutral particle. The dust particles are neutral and hence gets attracted by the compact disk which is wiped with a clean cloth.