Consider an LC circuit, with inductance L = 0 . 1   H and capacitance C = 10 - 3   F , kept on a…

Consider an LC circuit, with inductance L=0.1 H and capacitance C=10-3 F, kept on a plane. The area of the circuit is 1 m2. It is placed in a constant magnetic field of strength B0 which is perpendicular to the plane of the circuit. At time t=0, the magnetic field strength starts increasing linearly as B=B0+βt with β=0.04 T s-1. The maximum magnitude of the current in the circuit is____m A.

Solution

Emf induced in the circuit is

E=dϕdt=ddtB0+βtA

=β×A

=0.04 V

So the circuit can be rearranged as

Using Kirchhoff's law we can write

E=Ldidt+qC

Ldidt=E-qC

For maximum current, didt=0

Or q=CE

Using work energy theorem,

qE=12Li2+q22C

At imaxCEE=12Limax2+E2C22C

Or, imax=CLE

So, imax=10-3×0.040.1×10-3=4 mA

Asked in: JEE Advanced 2022 (Paper 1)

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