What is the value of flux in the section of yoke, if the pole flux is  Ф weber?

A. Ф x Ф
B. Ф^1/2
C. Ф/2
D. Ф
Answer --C


A 220 V d.c. shunt motor runs at 500 rpm when the armature current is 50 A. If the torque is doubled, the speed will be. (given that Ra= 0.2 )
(A) 500 r.p.m.
(B) 476 r.p.m
(C)576 r.p.m.
(D) 525 r.p.m.
Answer--B

The 'V' curve of synchronous motor shows the relationship between
(A) Applied voltage and back e.m.f.
(B) Back e.m.f. and armature current
 (C) Armature current and rotor field current
 (D) Back e.m.f. and power factor
Answer--C