Question

A child stands inside a large charged metal sphere. Will her hair stand on end?
A. Yes
B. No
C. Incomplete Information.
D. No guess about her hairstyle.

Answer 1

Hint: To answer this question we will first discuss the reasons for a person’s hair to stand up straight. Later, we shall discuss the principle and reasons of Van de Graff’s experiment. We shall then conclude by discussing why there can be no charge inside the conductor.

Complete step-by-step solution:
We know that two different objects with the same charge repel each other. This is the case with the famous balloon experiment for static electricity. When we rub the balloon on our head we are transferring the negatively charged particles to the tip of our hair. So, now as every tip of the hair has the same charge, they try to repel each other and in doing so, stand up straight. So, electric repulsion is the reason that causes our hair to stand up due to electric charge.
Now, if we think about the given sphere, it is given that the sphere is charged and it is metallic. This means that the sphere is a conductor. We know that there is no electric charge inside the conductor. Suppose there is a charge inside the conducting sphere, this will create an electric field inside the conductors causing the electrons to move and cancel out the electric field. Therefore, the charge inside the conductor will always be neutralized. Any excess charge on the conducting sphere must therefore be on the surface of the sphere and not on the inside.
Now, as there is no charge inside the charged metallic sphere, there is no charge that will be transferred to the hair of the person standing inside the sphere. As a result, the hair of the person inside the sphere won’t stand up.
Therefore, the correct answer is option B.

Note: There is a famous experiment known as Van de Graff’s experiment. In this experiment, if a person is touching the Van de Graff generator, his hair stands up. This phenomenon occurs as the charging generator transfers the charge to the hair follicles of the person touching it. The similarly charged follicles, therefore, stand up straight to repel each other.