Question

A student is provided with four objects:
A: a plastic comb
B: a rubber balloon
C: a copper rod
D: a woolen cloth
The object, that cannot be easily charged by rubbing, is the object labelled as—

Answer 1

A plastic comb is the answer

Answer 2

The object that cannot be easily charged by rubbing, is the object labelled as “ a copper rod”.

Explanation:

• Copper Rod is a metal and Metals are really not possible to be charged by friction.
• This is due to them having fixed cations in a sea of electrons (according to electron sea model).
• Just as the electrons are removed or added through friction, they get readjusted immediately.

• Thus, friction only works in the case of insulators. A plastic comb, a rubber balloon and a woollen cloth are all insulators by nature and they can be charged by the process of rubbing.