The plates each of area `A` of a parallel plate caoacitor are given charges `Q` and `-Q`. The plates are joined by a non-conducting spring of force constant `k`. The natural length of the spring is `d`, the inital separation between the plates. The left plate is connected to a vertical wall through a massless non-conducting rope and the right plate is connected to a block of mass `m` through similar rope. Assume the pulley to be massless, neglect dielectric effect of the spring and `Q^(2) lt 2mAepsilon_(0)g`.
If the block is released from rest, the maximum elongation of the string is

Options

A. `(2)/(k)(mg-(Q^(2))/(Aepsilon_(0)))`
B. `(2)/(k)(mg-(2Q^(2))/(Aepsilon_(0)))`
C. `(2)/(k)(mg-(Q^(2))/(2Aepsilon_(0)))`
D. None of these

Explanation

Time period is not affected by a constant force acting along the line of `SHM`.