Question

In an oscillating LC- 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) 
(B) 
(C) 
(D) Q

Answer 1

The answer is (C) \(\frac{Q}{\sqrt2}\)

Maximum charge on capacitor = q (Given)

The electric energy stored when energy in equally distributed, U'E = \(\frac{1}{2}.\frac{q^2}{C}\)

The energy stored in the capacitor when it is maximally charged, UE = \(\frac{1}{2}.\frac{Q^2}{C}\)

Thus,  

Ue = 2U'e

⇒ q = \(\frac{Q}{\sqrt2}\)

Therefore, the energy equally stored between both the field is \(\frac{Q}{\sqrt2}\) .