Question

When an ebonite rod is rubbed with fur, the charge acquired by the fur is ___________.
A. Positive
B. Negative
C. No charge
D. Can’t say

Answer 1

Hint: When an ebonite rod and fur are rubbed against each other, electrons from one surface get transferred to another surface. This transfer of electrons leads to excess of electrons on one surface while deficiency of electrons on another. The surface with excess electrons becomes negatively charged whereas the surface with deficiency of electrons becomes positively charged. Use these basics to answer this question.

Complete step by step answer:
When an ebonite rod is rubbed with fur, a chemical bond is formed between some parts of rod and fur. The electrons in the rod are more tightly bound as compared to fur. Thus, when they are rubbed against each other, electrons from fur are donated to the rod. As the rod is a bad conductor of electricity, the electrons from the rod do not come out. Now, the rod has excess electrons which makes it negatively charged. While the fur becomes deficient of electrons which makes it positively charged.
Hence, when an ebonite rod is rubbed with fur, the charge acquired by the fur is positive.
So, the correct answer is option A i.e. positive.

Note:
The charge on fur is equal and opposite to the charge on ebonite rod. This same phenomenon can be seen when an ebonite rod is rubbed with wool. If a glass rod is rubbed with silk cloth, the rod loses electrons which moves to silk cloth. This causes deficiency of electrons in glass rod which makes it positively charged whereas the silk cloth gains excess electrons due to which it becomes negatively charged.