Question

Energy of a changed capacitors is U. Now it is removed from a battery and then is connected to another identical uncharged. Capacitor in parallel. What will be the energy of each capacitor now?

• A. $\frac{3U}{2}$
• B. U
• C. $\frac{U}{4}$
• D. $\frac{U}{2}$

Answer 1

Answer: (C)

$\frac{U}{4}$

We know the energy of a capacitor in term of its charge $Q$ and capacitance $C$ is $\frac{Q^2}{2C}=U$

But, When it is removed from a battery and then is connected to another identical uncharged capacitor in parallel both capacitor will acquire charge equal to $\frac{Q}{2}$ in order to maintain same potential of both capacitor. So, energy of each capacitor is $\frac{Q^2}{2^2\times 2C}=\frac{U}{4}$.

Therefore C is correct option.