# DC Motor MCQs Part 2

DC Motor MCQs Part 2

## Which of following is a variable speed DC motor

Which of following is a variable speed DC motor:

1. Cumulatively compounded DC Motor
2. Differentially compounded DC Motor
3. Shunt DC Motor
4. Series DC Motor

Correct answer: 4. Series DC Motor

## When the speed of a DC motor increases, the armature current

When the speed of a DC motor increases, the armature current:

1. Remains constant
2. Increases
3. Decreases
4. None of the above

## With respect to the direction of rotation, the interpoles on a DC motor should have the same polarity as the main poles

With respect to the direction of rotation, the interpoles on a DC motor should have the same polarity as the main poles:

2. Behind them
3. Both of these
4. None of these

## Once a shunt motor is up to speed, the speed can be increased considerably by

Once a shunt motor is up to speed, the speed can be increased considerably by:

1. Decreasing field circuit resistance
2. Increasing armature circuit resistance
3. Increasing field circuit resistance

Correct answer: 3. Increasing field circuit resistance

## The field poles and armature of a DC motor are laminated in order to

The field poles and armature of a DC motor are laminated in order to:

1. Decrease the speed
2. Reduce eddy currents
3. Reduce the weight of the machine
4. Reduce armature reaction

Correct answer: 2. Reduce eddy currents

## Hot bearings of DC can happen due to

Hot bearings of DC can happen due to:

1. Dirty lubricant or lack of lubricant
2. Poor ventilation
3. Deviation from rated voltage
4. None of above

Correct answer: 1. Dirty lubricant or lack of lubricant

## The back EMF in DC motor

The back EMF in DC motor:

1. Aids the applied voltage
2. Aids the armature current
3. Opposes the applied voltage
4. None of the above

Correct answer: 3. Opposes the applied voltage

## DC shunt motors find practical applications where

DC shunt motors find practical applications where:

1. Practically constant speed is required
2. High starting torque is required
3. High no-load speed is required
4. Variable speed is required

Correct answer: 1. Practically constant speed is required