A loop with 10 turns and radius of 0.4 m is placed perpendicularly in a uniform magnetic field. A 40 V electromotive force is induced in the loop. After 10 s the radius of the loop is decreased to 0.2 m. Calculate the
(a) initial area of the loop.
(b)new area of the loop when it is decreased.
(c) magnitude of the magnetic field.