Electrostatics Question 186

Question: A charge $ Q $ is divided into two parts of $ q $ and $ Q-q $ . If the coulomb repulsion between them when they are separated is to be maximum, the ratio of $ \frac{Q}{q} $ should be [MP PET 1997]

Options:

A) 2

B) $ 1/2 $

C) 4

D) $ 1/4 $

Show Answer

Answer:

Correct Answer: A

Solution:

Let separation between two parts be r therefore $ F=k.q\frac{(Q-q)}{r^{2}} $

For F to be maximum $ \frac{dF}{dq}=0 $

therefore $ \frac{Q}{q}=\frac{2}{1} $



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