試題詳解

32. A conducting circular loop is placed in a uniform magnetic field of 0.04 T with its plane endicular to the magnetic field. The radius of the loop starts shrinking at 2 mm/s. emf in the loop when the radius is 2 cm is
(A) 0.8π μV
(B) 1.2π μV 
(C) 1.6π μV 
(D) 2.4π μV 
(E) 3.2π μV