Q. In an oscillations of $L$-$C$ circuit, the maximum charge on the capacitor is $Q$. The charge on the capacitor, when the energy is stored equally between the electric and magnetic field is
A) $\frac{Q}{2}$
B) $\frac{Q}{\sqrt{2}}$
C) $\frac{Q}{\sqrt{3}}$
D) $\frac{Q}{3}$
Explanation
(b) Maximum energy stored in the capacitor
$U_{\max} = \frac{Q^{2}}{2C}$
The energy is stored equally in electric and magnetic fields
So, energy in electric field
$E = \frac{1}{2}\left( \frac{Q^{2}}{2C} \right)$
Now, $\frac{Q^{'2}}{2C} = \frac{1}{2}\frac{Q^{2}}{2C}$
$\Rightarrow Q^{'} = \frac{Q}{\sqrt{2}}$
Reviewed by Dr. Abubacker
Physics Educator & NEET/JEE Specialist
Ph.D. in Physics with 19+ years of teaching experience.