A wire loop of radius 0.37 m lies so that an external magnetic field of magnitude 0.35 T is perpendicular to the loop. The field reverses its direction, and its magnitude changes to 0.20 T in 1.4 s. Find the magnitude of the average induced emf in the loop during this time

168.57 mV

Explanation:

Initial magnetic flux = BA , B magnetic field and A is area of loop

= .35 x 3.14 x .37²

= .15 Weber

Final magnetic flux

= - .2 x 3.14 x .37²

= -  .086 Weber

change in flux

.15 +  .086

= .236 Weber

rate of change of flux

= .236 / 1.4

= .16857 V

= 168.57 mV

if you already have the answer to (a), then just work out how many periods there are in 1 minute, and that's the answer to (c).

the answer is to check all of them! they all apply well at least i think so!