Question

A parallel plate capacitor is charged and the charging battery is then disconnected. If the plates of the capacitor are moved farther apart by means of insulating handle:

• A. the charge on the capacitor increases
• B. the voltage across the plates increases
• C. the capacitance increases
• D. the electrostatic energy stored in the capacitor increases

Answer 1

Answer: (B), (D)

The correct options are
B the voltage across the plates increases
D the electrostatic energy stored in the capacitor increases

When charging battery is disconnected the charge present on it is constant,
Q= constant
As d is increased C decreases $(C=\frac{{\epsilon }_{0}A}{d})$
$Q=C\cdot V.$
Q is constant, C decreases
$\Rightarrow$ V increases.
we know $E=\frac{Q^2}{2C.}$
as C is decreases
E increases.