Question

The attraction of a copper sphere towards a charged rod is easily explained in terms of the migration of electrons through the conducting foil. How can you explain the attraction of a piece of dry paper by the charged rod after rubbing it with hair?
(A) By electron migration within the paper and hair
(B) By distortion of individual atoms of paper and hair
(C) By proton migration within paper and hair
(D) Both (A) and (B)

Answer 1

Hint: To answer this question, first we should think how the rod is getting charged by rubbing it with the hair. Later, we should also see how the dry paper is getting attracted to the charged rod. If we can explain this with the help of the physics of static electricity, then the answer is ready.

Complete step-by-step answer:
Almost all the objects around us are electrically neutral in nature, in general. Because they contain an equal number of positive and negative charges in them. But when we rub any insulating rod, comb etc. they get charged due to the frictional force applied on them. The frictional force can cause the electrons to get transferred from one object to another. So, we can say that the rod is getting negatively charged when it is rubbed with hair, because of the transfer of electrons between the atoms. Here, we should remember that the protons are fixed to its place within the nucleus, but the electrons tend to move.
Later, when the charged rod is placed close to a piece of dry paper, the negative charge at the tip of the rod repels the negative charge on the paper and thereby attracts the positive charges close to it. This leads to the attraction of dry paper pieces against the rod.
So, the attraction of a piece of dry paper by the charged rod can be explained by the electron migration within the paper and hair.

The correct answer is option A.

Note: After sometime, the attracted pieces of dry paper fly away; because once they are in contact again the charges transfer to each other. Then, both the objects: paper and rod would have the same charge and they repel each other.