A parallel plate capacitor is connected to a battery as shown in figure. Consider two situations :
.
A : Key `K` is kept closed and plates of capacitors are moved apart using insulting handle.
B : Key `K` is opened and plates of capacitors are moved apart using insulting handle. Choose the correct options (s).

Options

A. In A : Q remains same but C changes.
B. In B : V remains same but C changes.
C. In A : V remains same and hence Q changes.
D. In B : Q remains same and hence V changes.

Answer

C, D

Explanation

In case A: when key is closed, the capacitor is connected to a battery and potential across the plates will remain constant. As `C=(epsilon_(0)A)/(d)` when separation between both the plates are increased, C decreases.
The charge on the capacitor is given by, `Q=CV`
From the above formula we can say, as C decreases Q also decreases.
In case B: When key is open the capacitor is no more connected to a battery and when plates are separated apart, the charge on the plates remains same and C decreases. Also, as `V=(Q)/(C )`, V increases as C decreases.