Help with Solenoids in Physics?

Question

A wire loop of radius 0.10 m lies so that an external magnetic field of magnitude 0.30 T is perpendicular to the loop. The field reverses its direction, and its magnitude changes to 0.10 T in 3.0 s. Find the magnitude of the average induced emf in the loop during this time.

Answer 1

Use: emf = - the change of the magnetic flux / time =
- {(BA)end - (BA)begin)}/ time