16. The scale of a PMMC instrument is uniform because of :
(A) effective eddy current damping
(B) no effect due to external magnetic fields
(C) spring control
(D) no hysteresis loss
17. In speed control of d.c. motors, armature voltage control and field current control are used to obtain speeds ____ base speed and ____ base speed respectively.
(A) below ; above
(B) below ; below
(C) above; above
(D) above ; below
18. A 6-pole d.c. generator runs at 1000 r.p.m. The frequency of current in the armature winding is:
(A) zero Hz
(B) 25 Hz
(C) 50 Hz
(D) 1000 Hz
19. One candle power of source of light emits _____
(A) one lumen/steradian
(B) one lumen/ radian
(C) one lumen/watt
(D) one lumen/meter
20. A voltage of 
is applied to half-wave rectifier circuit. The peak- inverse voltage (PIV) across the diode is :
(A) 2V
(B) 2√2
(C) V/√2
(D) √2V