Question

Which of the following cannot be charged easily by friction?
A. A plastic scale
B. A copper rod
C. An inflated balloon
D. A woollen cloth

Answer 1

Hint: When two bodies are rubbed with each charge transfer takes place due to friction. We can charge only non-conductive materials which do not conduct electricity by friction. The conductive materials which can conduct electricity are very hard to charge by friction.

Detailed step by step answer:
There are two types of charge in nature: positive charge and negative charge. The materials which can conduct charge through them are called conductors while those materials which cannot conduct charge through them are called insulators.
We can transfer charge from one body to another through the process of rubbing two materials with each other. When two objects are rubbed with each other, friction comes into action. The atoms of the one material interact with atoms of other material due to friction as a result electrons are transferred from one body to another. The body gets negatively charged and when a positively charged body comes in contact with this body then charges will get neutralized and crackling will take place.
Now if the two bodies that are being rubbed together are bad conductors then the charge will accumulate on the surface of that material but if a material is a good conductor then the electrons that are being transferred to it will be conducted to the other parts of the material and the material will not get charged.
Since, copper is a good conductor, it will not get charged easily. So, the correct answer is option B.

Note: When two bodies are rubbed with each other, the charge transfer takes place in such a way that the material which has shortage of electrons attracts the electrons from the material which has electrons in excess.