A figure shows a closed loop of wire that consists of a pair of equal semicircles, of radius 6.1 cm, lying?

a figure shows a closed loop of wire that consists of a pair of equal semicircles, of radius 6.1 cm, lying in mutually perpendicular planes. The loop was formed by folding a flat circular loop along a diameter until the two halves became perpendicular to each other. A uniform magnetic field of magnitude 85 mT is directed perpendicular to the fold diameter and makes equal angles (of 45°) with the planes of the semicircles. The magnetic field is reduced to zero at a uniform rate during a time interval of 11 ms. During this interval, what are the (a) magnitude (in mV) and (b) direction (clockwise – show “1″ or counterclockwise – show “0″ when viewed along the direction of ) of the emf induced in the loop?

Both half-circular surfaces are at an angle of 45 degrees to the filed. Hence the flux of a field B is

flux = B * pi R^2 * sin(45) = 1/2 sqrt(2) * pi * R^2 * B

This flux goes to zero in 11 ms.

Hence Faraday’s law gives:

Emf = Delta(flux) / delta t
= 1/2 sqrt(2) * pi * (0.061m)^2 * 85*10^-3 T / (11* 10^(-3) s)
=6.39 mV

The direction of the current will be such as to counteract the diminishing flux. You can figure that out.

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