Question

If the charge on the condenser of $10\mu F$ is doubled, then the energy stored in it becomes ____________.

• A. Zero
• B. Twice that of initial energy
• C. Half the initial energy
• D. Four times the initial energy

Answer 1

The correct option is D Four times the initial energy

Let the charge on the capacitor of capacitance $C$ be $Q$.

Energy stored in the capacitor $E=\frac{Q^2}{2C}$

$⟹$ $E\propto Q^2$

Thus if the charge on the condenser (capacitor) is doubled, then the energy stored in it becomes four times that of initial energy.