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//q' = 2`
B. `q//q' = 1`
C. `q//q' = 4`
D. `q//q' = 3`

Answer

B

Explanation

Here, `q + q' = Q- q :. F = (K q q')/(r^(2))`
`F = (K q(Q - q))/(r^(2))`, Fro `F` to be the maximum `(dF)/(dq) = 0`
`(d)/(dq) [(K q(Q - q))/(r^(2))] = 0` or `(d)/(dq) [(kqQ - kq^(2))/(r^(2))] = 0`
`:. KQ - 2 Kq = 0`
or `q = (Q)/(2)` and `q' = (Q)/(2)` so `(q)/(q') = 1`