Question

Imagine you have a circular solenoid with N = 50 turns. The
solenoid has a diameter of di = 1.5 cm, and the length of the coil
is L = 35 cm. The coil is perpendicular to a uniform magnetic field
of B = 0.75 T, and suddenly increases in diameter (remaining
circular) from di = 1.5 cm to df = 3.0 cm over the course of 1
second. The coil has a resistance of 0.68 W. What are the
magnitudes and directions of the induced current and magnetic
field?
I have done this so far:Flux per turn=BA
A=pi*d^2/4
Ind EMF=N*d(flux)/dt
E=NB(Theta A)/t=(N*B*pi)*(df^2-di^2)/4*t
I=e/R
I=(50)*(0.75T)(pi)(0.03^2-0.015^2)/(4*1*0.68)
I=0.0292 A

Answer 1