Question

A capacitor of capacitance $C$ has charge $Q$ and stored energy $W$. If the charge is increased to $2Q$, the stored energy would be:

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

Answer 1

The correct option is D $4W$

We know that the energy stored in a capacitor is given by:

$W=\frac{Q^2}{2C}$

Now, if the charge $Q$ increases to $2Q$,

then the change in energy will be given by:

$W^{\prime }=\frac{(2Q{)}^2}{2C}$

$\Rightarrow \frac{4Q^2}{2C}$$=4W$