Physics Circle home Student Login

Home›Chapters›Alternating Current PYQs›LC Oscillations›Question 22

JEE Main 2011 (AIEEE) · LC Oscillations

LC Oscillations question from JEE Main 2011 (AIEEE)

Q22JEE Main 2011 · AIEEEMedium

LC Oscillations

A fully charged capacitor CC with initial charge q0q_0 is connected to a coil of self inductance LL at t=0.t = 0. The time at which the energy is stored equally between the electric and the magnetic fields is:

Show answer and solution

Answer: (a)

  1. q=q0cos⁡ωtq = q_0\cos\omega t with ω=1LC\omega = \frac{1}{\sqrt{LC}}.
  2. Equal energies when q=q02⇒cos⁡ωt=12⇒ωt=π4q = \frac{q_0}{\sqrt{2}} \Rightarrow \cos\omega t = \frac{1}{\sqrt{2}} \Rightarrow \omega t = \frac{\pi}{4}
  3. t=π4LCt = \frac{\pi}{4}\sqrt{LC}
  4. So the answer is (a).
Report a mistake

More questions on LC Oscillations