JEE Mains 2020 Model Paper 2 New Pattern

The plates each of area A of a parallel plate capacitor are given charges Q and –Q. The plates are free to move on the horizontal frictionless surface and joined by nonconducting spring of force constant ‘k’. The natural length of the spring is ‘d’, which is equal to the initial 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’ thorough similar rope. Assume the pulley massless, neglect dielectric effect of the spring and Q2 < 2mAε0g. If block is released from rest, the maximum elongation of the spring is :