A Coil Is Wrapped with 300 Turns of Wire on the Perimeter

Multiple Choice

A coil is wrapped with 300 turns of wire on the perimeter of a circular frame (radius = 8.0 cm) . Each turn has the same area, equal to that of the frame. A uniform magnetic field is turned on perpendicular to the plane of the coil. This field changes at a constant rate from 20 to 80 mT in a time of 20 ms. What is the magnitude of the induced emf in the coil at the instant the magnetic field has a magnitude of 50 mT?

A) 24 V
B) 18 V
C) 15 V
D) 10 V
E) 30 V