Types of DC Motors: A Comprehensive Guide for Electrical Technology Students

Question 1

Which type of DC motor maintains a constant field current and a variable armature current?

Accepted Answer

Shunt motor

Answer

Series motor

Answer

Compound motor

Question 2

Which characteristic is unique to series motors?

Accepted Answer

High starting torque

Answer

Constant speed

Answer

Low efficiency

Question 3

Which type of DC motor exhibits a combination of shunt and series motor characteristics?

Accepted Answer

Compound motor

Answer

Permanent magnet motor

Answer

Stepper motor

Question 4

What is the significance of back EMF in the operation of a DC motor?

Accepted Answer

It opposes the applied voltage

Answer

It reduces motor efficiency

Answer

It determines motor torque

Question 5

Which equation accurately represents the relationship between torque (T), current (I), and flux (Φ) in a DC motor?

Accepted Answer

T = kΦI

Answer

I = kT/Φ

Answer

Φ = kT/I

Question 6

Which application commonly utilizes shunt motors?

Accepted Answer

Electric fans

Answer

Power tools

Answer

Traction motors

Question 7

What is the impact of increasing the field current in a shunt motor?

Accepted Answer

Increased speed

Answer

Decreased torque

Answer

No impact

Question 8

In a DC motor, which component primarily establishes the magnetic field?

Accepted Answer

Field coil

Answer

Armature

Answer

Commutator

Answer

Brush

Question 9

What is the primary advantage of using a compound motor over a shunt motor?

Accepted Answer

Improved starting torque

Answer

Reduced sparking at the brushes

Answer

Higher operational efficiency

Answer

Lower operating temperature

Question 10

Which type of DC motor is preferred for applications that necessitate precise speed control?

Accepted Answer

Shunt motor

Answer

Series motor

Answer

Compound motor

Answer

Universal motor

Question 11

What is the function of the commutator in a DC motor?

Accepted Answer

Reverses the direction of current

Answer

Regulates the flow of current

Answer

Provides mechanical support

Answer

Stores electrical energy

Question 12

Which of the following is not a common application for DC motors?

Accepted Answer

Refrigerators

Answer

Electric vehicles

Answer

Power tools

Answer

Industrial machinery

Question 13

Which defining characteristic distinguishes series DC motors from other types?

Accepted Answer

Enhanced starting torque

Answer

Reduced operating speed

Answer

Self-regulating properties

Answer

Capability for reversible rotation

Question 14

Which type of DC motor is most suitable for maintaining constant speed under varying load conditions?

Accepted Answer

Shunt motor

Answer

Series motor

Answer

Compound motor

Answer

Permanent magnet motor

Question 15

What is the primary purpose of brushes in a DC motor?

Accepted Answer

Conveying current to the armature

Answer

Connecting field windings to the power source

Answer

Providing mechanical support to the armature

Answer

Adjusting the motor's speed

Question 16

What is the function of the commutator in a DC motor?

Accepted Answer

Reversing current direction in the armature

Answer

Controlling motor speed

Answer

Generating the magnetic field

Answer

Providing electrical insulation

Question 17

Which type of DC motor maintains a relatively constant speed over varying loads?

Accepted Answer

Shunt motor

Answer

Series motor

Answer

Compound motor

Answer

Permanent magnet DC motor

Question 18

What is the primary purpose of the commutator in a DC motor?

Accepted Answer

To reverse the direction of current flow in the armature

Answer

To maintain a strong magnetic field in the stator

Answer

To regulate the speed of the motor

Answer

To provide structural support to the armature

Question 19

Which DC motor type is most suitable for applications requiring high starting torque?

Accepted Answer

Series motor

Answer

Shunt motor

Answer

Compound motor

Answer

Permanent magnet DC motor

Question 20

What is the key distinction between a shunt motor and a series motor?

Accepted Answer

Field winding connection

Answer

Armature winding connection

Answer

Commutator design

Answer

Stator construction

Question 21

What is the purpose of a starter in a DC motor circuit?

Accepted Answer

To limit the initial starting current

Answer

To protect the motor from overloads

Answer

To reverse the direction of rotation

Answer

To adjust the motor speed

Question 22

What is the function of a flywheel in a DC motor system?

Accepted Answer

To minimize speed fluctuations

Answer

To store excess energy

Answer

To increase torque output

Answer

To prevent overloads

Question 23

In a compound motor, what is the primary purpose of the compensating winding?

Accepted Answer

To mitigate armature reaction

Answer

To enhance speed regulation

Answer

To amplify starting torque

Answer

To diminish power factor

Question 24

For applications that demand substantial starting torque, which type of DC motor is the most suitable?

Accepted Answer

Series motor

Answer

Shunt motor

Answer

Compound motor

Answer

Universal motor

Question 25

What is the effect of increasing the field current in a shunt motor?

Accepted Answer

Augmented speed and diminished torque

Answer

Diminished speed and augmented torque

Answer

Augmented speed and augmented torque

Answer

Diminished speed and diminished torque

Question 26

Which of the following applications commonly utilizes a universal motor?

Accepted Answer

Household appliances

Answer

Large-scale industrial machinery

Answer

Electric vehicles

Answer

Specialized medical devices

Question 27

Which of the listed options is not a type of DC motor?

Accepted Answer

Induction motor

Answer

Shunt motor

Answer

Series motor

Answer

Compound motor

Question 28

What is the primary function of field windings in a DC motor?

Accepted Answer

Generation of the magnetic field

Answer

Control of motor speed

Answer

Production of electrical current

Answer

Provision of mechanical support

Question 29

How is the torque produced by a DC motor related to the armature current?

Accepted Answer

Directly proportional

Answer

Inversely proportional

Answer

Logarithmic

Answer

No relationship

Question 30

What is the purpose of the commutator in a DC motor?

Accepted Answer

Reversal of current flow direction

Answer

Provision of mechanical support

Answer

Regulation of motor speed

Answer

Generation of the magnetic field

Question 31

Which characteristic is unique to shunt motors?

Accepted Answer

Constant speed

Answer

High starting torque

Answer

Low starting current

Answer

Used in applications requiring variable speed

Question 32

Which type of DC motor is most suitable for applications that require a high initial force to start?

Accepted Answer

Series motor

Answer

Shunt motor

Answer

Compound motor

Answer

Permanent magnet motor

Question 33

What is the primary role of the commutator in a DC motor?

Accepted Answer

Reverses the direction of current flow

Answer

Converts AC to DC

Answer

Controls the speed of the motor

Answer

Provides electrical isolation

Question 34

Which type of compound motor exhibits a cumulative effect, resulting in enhanced torque?

Accepted Answer

Short shunt

Answer

Lap wound

Answer

Wave wound

Answer

Long shunt

Question 35

What is the main function of interpoles in a DC motor?

Accepted Answer

Reduce sparking

Answer

Increase torque

Answer

Control speed

Answer

Reverse direction

Question 36

Which of the following is a potential disadvantage of using series motors?

Accepted Answer

Variable speed

Answer

High starting torque

Answer

Compact size

Answer

Low maintenance

Question 37

How is the torque produced by a DC motor related to the strength of the magnetic field?

Accepted Answer

Directly proportional

Answer

Inversely proportional

Answer

Independent

Answer

Logarithmically related

Question 38

In which type of DC motor does the field current remain constant regardless of the load?

Accepted Answer

Shunt motor

Answer

Permanent magnet motor

Answer

Series motor

Answer

Compound motor

Question 39

What is the key advantage of a series motor?

Accepted Answer

High starting torque

Answer

Low maintenance

Answer

Constant speed

Answer

High efficiency

Question 40

Which DC motor type combines the features of both shunt and series motors?

Accepted Answer

Compound motor

Answer

Synchronous motor

Answer

Permanent magnet motor

Answer

Stepper motor

Question 41

What is the main function of the commutator in a DC motor?

Accepted Answer

To change the direction of current in the armature winding

Answer

To control motor speed

Answer

To generate the magnetic field

Question 42

Which application is best suited for a shunt motor?

Accepted Answer

Driving a lathe

Answer

Operating a fan

Answer

Lifting heavy loads

Answer

Starting a car engine

Question 43

What is the defining feature of a permanent magnet DC motor?

Accepted Answer

It doesn't have a field winding

Answer

Low maintenance

Answer

Variable speed

Answer

High starting torque

Question 44

Which type of DC motor is commonly found in small appliances and toys?

Accepted Answer

Permanent magnet motor

Answer

Series motor

Answer

Compound motor

Answer

Shunt motor

Question 45

What is the primary disadvantage of a series motor?

Accepted Answer

High armature current when the load is low

Answer

Constant speed

Answer

Excessive sparking

Answer

Low starting torque

Question 46

Which winding in a DC motor produces the main magnetic field?

Accepted Answer

Field winding

Answer

Armature winding

Answer

Compensation winding

Answer

Commutator winding

Question 47

What is the main purpose of a starter in a DC motor?

Accepted Answer

To limit the starting current

Answer

To reverse the direction of rotation

Answer

To increase the speed