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} $
