Question

A circular loop in the plane of the paper lies in a 0.78 T magnetic field pointing into the paper.

A) What is the magnitude of the average induced emf? Answer in V.

B) If the coil resistance is 4.3 ohm , what is the average induced current? Answer in A

Answer 1

I think you have missed the other information mentioned in the problem. I think the missing information should be the loop diameter changes from d1 to d2 in time t seconds.

You have given the value of B = 0.78 T

So, for the part (A) -

The expression of the induced emf is -

V = dø / dt = 0.78 . ( ? . (d1/2)^2 – ? .(d2/2)^2 ) / t

put the values of d1, d2 and t, you will get the result.

For the part (B) -

Coil resistance R = 4.3 Ohm

So, avearge induced current I = V / R = (put the value of V calculated in part A) / 4.3