Q.
Two large insulating plates having surface charge densities $+ \, \sigma $ and $-\sigma $ are fixed at a distance $d$ from each other. A small test charge $q$ of mass $m$ is attached to two identical springs as shown in the figure. The charge $q$ is now released from rest with springs in natural length. Then $q$ will (neglect gravity)

NTA AbhyasNTA Abhyas 2020Electrostatic Potential and Capacitance
Solution: