Question

A Cat’s skin acquires __________charge when rubbed with ebonite rod.
A. negative
B. positive
C. zero
D. cannot say

Answer 1

Hint:Electric charge refers to the physical property of matter which causes it to experience a force when actually placed in an electromagnetic field. Electric charge is of two types i.e. positive and negative. It should be noted that like charges always repel each other whereas unlike charges always attract each other.

Complete answer:
The gain of negative charge or a positive charge, when two materials are rubbed depends on the relative electron affinity of the two materials. The one having positive electron affinity will get positively charged while the other having relatively negative electron affinity will get negatively charged. So wool will lose the electrons on rubbing with glass rod and gets positively charged as per its macroscopic properties whereas the glass rod gets negative charge by gaining those electrons. So basically it depends on what their electron affinities are or on what materials we are using for rubbing.
When we rubbed ebonite rod with fur or wool then that process is called induction. In this case both have the same magnitude but with opposite charges. The cat’s skin can be considered as fur. When we rub fur with an ebonite rod, the chemical bond is formed between some parts of the surface. Rod bound electrons more tightly than fur. So, fur donates electrons to the rod while rod won’t donate electrons. Rod becomes negatively charged due to excess of electrons while the fur with lost electrons becomes deficient of electrons. Thus, fur becomes positively charged. So we can say that a cat's fur acquires a positive charge when rubbed with an ebonite rod.

Hence, the correct answer is option B.

Note: It should be noted that ebonite rod is made from special vulcanized rubber and it has the tendency to collect negative charges over its surface. And thus, the electrons in ebonite are more tightly bound in comparison to that of fur due to which it acquires the negative charge.