DC Motor MCQs Part 1

DC Motor MCQs Part 1

A DC Motor converts

A DC Motor converts:

1. DC power to AC power
2. DC to Mechanical Power
3. Mechanical Power to DC
4. AC power to DC power

Correct answer: 2. DC to Mechanical Power

Carbon brushes are preferable over copper brushes since

Carbon brushes are preferable over copper brushes since:

1. They have longer life
2. They reduce sparking
3. They reduce armature reaction
4. They have lower resistance

Correct answer: 2. They reduce sparking

The speed of a which type of DC motor is practically constant

The speed of a which type of DC motor is practically constant

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

Correct answer: 3. Shunt motor

The greatest percentage of power loss in DC motor is due to

The greatest percentage of power loss in DC motor is due to:

1. Core loss
2. Windage loss
3. Friction loss
4. Copper loss

Correct answer: 4. Copper loss

The demand for large increase in torque of a DC. series motor is met by

The demand for large increase in torque of a DC. series motor is met by:

1. Large decrease in current
2. Small decrease in speed
3. Large decrease in speed
4. Large increase in speed

Correct answer: 3. Large decrease in speed

Speed control by variation of field flux results in

Speed control by variation of field flux results in:

1. Constant power drive
2. Variable torque drive
3. Constant torque drive
4. Variable power drive

Correct answer: 1. Constant power drive

Running speed of DC series motor is determined from

Running speed of DC series motor is determined from

1. Load
2. Field excitation
3. Armature resistance
4. None of these

Correct answer: 1. Load

The speed of DC motor is

The speed of DC motor is:

1. Inversely proportional to flux per pole
2. Directly proportional to flux per pole
3. Inversely proportional to applied voltage
4. None of these

Correct answer: 1. Inversely proportional to flux per pole

DC motors are still used in industrial applications since they

DC motors are still used in industrial applications since they:

1. Are cheap
2. Provide fine speed control
3. Are simple in construction
4. None of these

Correct answer: 2. Provide fine speed control

Armature reaction in DC motor is increased

Armature reaction in DC motor is increased

1. When the armature current decreases
2. When the field current increases
3. When the armature current increases
4. By interpoles

Correct answer: 3. When the armature current increases