Three large plates are arranged as shown. How much charge will flow through the key k if it is closed?

Options

A. `(Q_(0)^(2)b)/(4S epsilon_(0))`
B. `(Q_(0)^(2)b)/(8S epsilon_(0))`
C. `(Q_(0)^(2)b)/(2S epsilon_(0))`
D. `(3Q_(0)^(2)b)/(4S epsilon_(0))`

Explanation

Finally the charge on either capacitor is `Q_0//2`.Hence heat produced is = initial P.E.-final P.E.
`=Q_0^2/(2C)-(Q_0//2)^2/(2C)-(Q_0//2)^2/(2C)=(Q_0^2b)/(4Sepsilon_0)`