53. A stiff wire bent into a semicircle of radius a = 2.0 cm is rotated at constant angular speed 40 rev/s in a uniform 20 mTmagnetic field. What is the amplitude of the emf induced in the loop?
(A) 3.16 × 10-2 V
(B) 3.16 × 10-3 V
(C) 3.16 × 10-1 V
(D) 1.98 × 10-2 V
(E) 1.98 × 10-3 V