Physics

Problem

A small circular loop of wire of radius

a

is located at the centre of a much larger circular wire loop of radius

b

. The two loops are in the same plane. The outer loop of radius

b

carries an alternating current

I = I_0 \cos(\omega t)

. The emf induced in the smaller inner loop is nearly: a.

\frac{\pi\mu_0 I_0}{2} \cdot \frac{a^2}{b} \omega \sin(\omega t)

\frac{\pi\mu_0 I_0}{2} \cdot \frac{a^2}{b} \omega \cos(\omega t)

\pi\mu_0 I_0 \frac{a^2}{b} \omega \sin(\omega t)

\frac{\pi\mu_0 I_0 b^2}{a} \omega \cos(\omega t)