Question

Select correct alternative(s)
If both plates of parallel plate capacitor are given positive charge as shown in figure and at $t=0$ switch is closed:

• A. Current in resistance 'R' will flow from A to B
• B. Current in resistance 'R' will flow from B to A
• C. Current in the circuit at t is $\frac{Q}{2RC}{e}^{-t/RC}$
• D. Total heat developed in the circuit long after switch is closed is $\frac{Q^2}{4C}$

Answer 1

Answer: (B), (C)

Current in the circuit at t is $\frac{Q}{2RC}{e}^{-t/RC}$

Charge redistribution on the capacitor plates is as shown below,

Charge variation on capacitor is
$Q\left(t\right)=\frac{Q}{2}(1-e^{-t/RC})$
Current flow in the circuit is
$i\left(t\right)=\frac{Q}{2RC}{e}^{-t/RC}$ (from B to A)
Heat developed in the circuit is
$\Delta H=\frac{(Q/2{)}^2}{2C}$