two identical metal plates of area A arranged parallel to each other. the lower plate is held fixed and theupper plate is connected at its middle to one end of a spring of a spring force k. the other end of the spring is attached to a fixed support. when either f the plates has no charge, the equilibrium separation between them is d. now the switch is switched on to apply a voltage V between the plates. What is the maximum voltage V that can be applied as long as the plates dont touch each other?