MCQs on Electrical Test

Ideal value of voltage regulation of a device is?

Select one:

• a. 0
• b. ∞
• c. a finite negative value
• d. a positive finite value

With the increase in speed of a DC motor

Select one:

• a. both back emf as well as line current increase.
• b. back emf increases but line current falls.
• c. both back emf as well as line current fall
• d. back emf falls and line current increases

The effect of ------------------ on main field flux is armature reaction?

Select one:

• a. armature mmf
• b. armature current
• c. armature flux
• d. all of the above

For a dc machine shunt resistance and armature resistance values are

• Select one:
• a. high and low
• b. low and high
• c. low and low
• d. high and high

If terminal voltage of one 1000 rpm shunt motor is reduced to half the speed of the motor will be

• 500 rpm
• 250 rpm
• 1000 rpm
• 2000 rpm

In DC machine torque depends on which of the following? 

•  flux (φ) 
•  armature current (I) 
•  both A and B 
•  speed

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