Exam Question

(a) Derive an expression for the e.m.f induced in an a.c. generator. (6)

(b) A 220 V, d.c. shunt motor has an armature resistance of 0.5 ohm and an armature current of 40 A on full load. Determine the reduction in flux necessary for a 50 percent reduction in speed. The torque for both conditions can be assumed to remain constant. (10)