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← JEE Main 2022 · 28 Jun · Shift 2
PhysicsSingle correct+4 / -1Question 44 of 90

JEE Main 2022 · 28 Jun · Shift 2, Physics question 44

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.)

Choose one option
Answer and worked solution

Official answer: D

Scaling. emf ∝N\propto N; resistance ∝N⋅(length per turn)rw2\propto\dfrac{N\cdot(\text{length per turn})}{r_w^2}.

Power ε2R∝Nrw2\dfrac{\varepsilon^2}R\propto Nr_w^2: halving NN and doubling rwr_w doubles it.

(D)