A:-2Vm

B:-Vm

C:-Vm/2

D:-3Vm

Correct Answer:- Option-A

Question69:-The number of comparators required in a 3 bit comparator type ADC is

൧:-6
-7
C:-3
D:-8
Correct Answer:- Option-B

Question70:-The rotor of a stepper motor has no

A:-Windings
B:-Commutator
C:-Brushes

D:-Alll of these

Correct Answer:- Option-D

Question71:-Which method of speed control cannot be used in a permanent magnet dc motor

A:-Armature voltage variation
B:-Armature resistance control
C:-Varying the field current
D:-All of the above

Correct Answer:- Option-C

Question72:-Which test on a transformer provides information about regulation, efficiency and heading under load
conditions.

A:-open circuit test
B:-short circuit test
C:-Hopkinsons test
D:-back to back test
Correct Answer:- Option-D

Question73:-In a transformer the resistance between primary and secondary must be

A:-zero

Question74:-V curves for a synchronous motor represent relation between

A:-field current and speed

ield current and power factor
C:-Armature current & field current
D:-Power factor and speed

Correct Answer:- Option-C

Question75:-An induction motor is expected to take largest starting current under which method of starting

A:-Direct online starting
B:-Starter-rotor starting
C:-star-delta starting
D:-Auto-transformer starting
Correct Answer:- Option-A

Question76:-The starting capacitor of a single phase motor is

A:-Electrolytic capacitor
B:-Ceramic capacitor
:-Paper capacitor
D:-none of these

Correct Answer:- Option-A

Question77:-An elevator drive is required to operate in

A:-One quadrant only
B:-Two quadrant only
C:-Three quadrants only
D:-Four quadrants only