At the center of a fixed large circular coil of radius R, a much… | JEE Main 2018 (15 Apr, Shift 2)

Q57JEE Main 2018 · 15 APR · SHIFT 2Difficult

Mutual Inductance

At the center of a fixed large circular coil of radius R, a much smaller circular coil of radius r is placed. The two coils are concentric and are in the same plane. The larger coil carries a current I. The smaller coil is set to rotate with a constant angular velocity $\omega$ about an axis along their common diameter. Calculate the emf induced in the smaller coil after a time t of its start of rotation.

Show answer and solution

Answer: (a)

Field at the centre: $B = \frac{\mu_0 I}{2R}$ , uniform over the small coil.
As the coil rotates: $\phi = B\pi r^2\cos\omega t$
$e = -\frac{d\phi}{dt} = \frac{\mu_0 I}{2R}\,\omega\pi r^2 \sin\omega t$
So the answer is (a).

Report a mistake

More questions on Mutual Inductance

A small circular loop of wire of radius a is located at the centre of a much larger…JEE Main 2017 (8 Apr, Shift 1)
Two coils, X and Y, are kept in close vicinity of each other. When a varying current…JEE Main 2013 (9 Apr, Shift 1)
A circular loop of radius 0.3 cm lies parallel to a much bigger circular loop of radius…JEE Main 2013
Two coaxial solenoids are made by winding thin insulated wire over a pipe of…JEE Main 2008 (AIEEE)
Two coils of self inductance 2 mH and 8 mH are placed so close together that the…NEET 2006 (AIPMT)
Two coils are placed close to each other. The mutual inductance of the pair of coils…JEE Main 2003 (AIEEE)
Two coils have a mutual inductance of 0.005 H. The current changes in the first coil…NEET 1998 (AIPMT)
Two coils P and Q are separated by some distance. When a current of 3 A flows through…MHT CET 2026 (15 May, Shift 2)

Mutual Inductance question from JEE Main 2018 (15 Apr, Shift 2)

More questions on Mutual Inductance