A certain charge Q is divided into two parts q and `Q-q`, wheich are then separated by a cetain distance. What must q be in terms of Q to maximum the electrostatic repulsion between the two charges?

Options

A. Q=2q
B. Q=3q
C. Q=4q
D. Q=4q+c

Answer

a

Explanation

The electrostacitc force of repulsion between the charge and (Q-q) at separation r is given by
`F=(1)/(4piepsilon_(0))(qQ-q)/(r^(2))=(1)/(4piepsilon_(0)).(Q-2q)/(r^(2))=0`
as `(1)/(4piepsilon_(0)r^(2)) is constant, therefore,Q -2q=0 or Q=2q`