Physics Circle home Student Login

Home›Chapters›Electromagnetic Induction PYQs›Magnetic Flux & Faraday's Law›Question 58

JEE Main 2022 (28 Jun, Shift 2) · Magnetic Flux & Faraday's Law

Magnetic Flux & Faraday's Law question from JEE Main 2022 (28 Jun, Shift 2)

Q58JEE Main 2022 · 28 JUN · SHIFT 2Medium

Magnetic Flux & Faraday's Law

A coil is placed in a time varying magnetic field. If the number of turns in the coil were to be halved and the radius of wire doubled, the electrical power dissipated due to the current induced in the coil would be:

(Assume the coil to be short circuited.)

Show answer and solution

Answer: (d)

  1. e∝Ne \propto N (same coil area, same dB/dtdB/dt).
  2. Wire length ∝N\propto N, so R=ρLπr2∝Nr2R = \dfrac{\rho L}{\pi r^2} \propto \dfrac{N}{r^2}.
  3. P=e2R∝N2r2N=Nr2P = \dfrac{e^2}{R} \propto \dfrac{N^2 r^2}{N} = N r^2.
  4. N→N/2N \to N/2, r→2rr \to 2r: P′=12×4 P=2PP' = \dfrac{1}{2}\times 4\,P = 2P. So the answer is (d) Doubled.
Report a mistake

More questions on Magnetic Flux & Faraday's Law