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At t = 0, a capacitor of capacitance C carrying an initial charge q0 is joined to an inductor of self-inductance L. The instant when the energy is shared equally by the electric field and the magnetic field is
- (π/4)√LC
- 2π√LC
- √LC
- π√LC
Correct answer: (π/4)√LC
Solution
Capacitor energy ~ q^2 = q0^2*cos^2(wt) with w=1/sqrt(LC). Equal sharing of energy needs cos^2(wt)=1/2, i.e. wt=pi/4, so t = (pi/4)*sqrt(LC).
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