An emf is induced in a conducting loop of wire 1.24 m long as its shape is changed from square to circular. Calculate the average magnitude of the induced emf if the change in shape occurs in 4.21 s, and the local 0.123 T magnetic field is perpendicular to the plane of the loop.

Answer 1

Emf = d(Flux)/dt

In this case, the area changes but B stays the same.
d(Flux)dt = B*d(Area)/dt

The area change is d(Area) = (circle area - square area)