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

Question 1

What is the purpose of a capacitor in a single-phase induction motor?

Accepted Answer

To improve starting torque

Answer

To reduce noise

Answer

To increase efficiency

Question 2

Which of the following is not a type of AC motor?

Accepted Answer

Brushed DC motor

Answer

Synchronous motor

Answer

Induction motor

Question 3

Which type of motor is best suited for applications requiring precise positioning?

Accepted Answer

Stepper motor

Answer

DC shunt motor

Question 4

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

Accepted Answer

Controls the direction of current flow

Answer

Provides a rotating magnetic field

Question 5

What is the purpose of a stator in an electric motor?

Accepted Answer

Generates a rotating magnetic field

Answer

Converts electrical energy into mechanical energy

Question 6

Increasing the number of poles in a motor results in:

Accepted Answer

Increased motor torque

Answer

Increased motor speed

Answer

Reduced motor efficiency

Answer

No change in motor characteristics

Question 7

The key distinction between a closed-loop and an open-loop control system for electric motors is that:

Accepted Answer

Closed-loop systems incorporate feedback to maintain desired performance, while open-loop systems do not.

Answer

Open-loop systems are more efficient than closed-loop systems.

Answer

Closed-loop systems are exclusively applicable to DC motors.

Answer

Open-loop systems offer greater precision than closed-loop systems.

Question 8

Which of the following is NOT a type of AC motor?

Accepted Answer

Brushless DC motor

Answer

Induction motor

Answer

Synchronous motor

Answer

Stepper motor

Question 9

In industrial settings, which type of motor is commonly employed?

Accepted Answer

Induction motor

Answer

DC motor

Answer

Stepper motor

Answer

Universal motor

Question 10

The primary difference between a brushed and brushless DC motor is that:

Accepted Answer

Brushless motors utilize a permanent magnet.

Answer

Brushed motors exhibit higher efficiency.

Answer

Brushed motors offer greater durability.

Answer

Brushless motors have a larger size.

Question 11

The main advantage of a synchronous motor over an induction motor is its:

Accepted Answer

Higher efficiency

Answer

Ability to operate at varying speeds

Answer

Quieter operation

Answer

Compact size

Question 12

A characteristic feature of a shaded-pole motor is its:

Accepted Answer

Low starting torque

Answer

High starting torque

Answer

Wide speed range

Answer

High power output

Question 13

In a DC motor, the commutator serves the purpose of:

Accepted Answer

Reversing the direction of current flow

Answer

Converting AC to DC

Answer

Adjusting the motor's speed

Answer

Enhancing the motor's torque

Question 14

Which of the following parameters does NOT affect the speed of an AC motor?

Accepted Answer

Motor efficiency

Answer

Power supply frequency

Answer

Number of poles

Answer

Load on the motor

Question 15

Hair dryers typically utilize which type of motor?

Accepted Answer

Universal motor

Answer

Induction motor

Answer

Stepper motor

Answer

Synchronous motor

Question 16

When working with electrical motors, which safety precaution holds the utmost importance?

Accepted Answer

Disconnecting power before servicing

Answer

Wearing safety glasses

Answer

Using appropriate tools

Answer

Avoiding contact with moving parts

Question 17

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

Accepted Answer

DC motor

Answer

Induction motor

Answer

Synchronous motor

Answer

Stepper motor

Question 18

Compared to AC motors, what primary advantage do DC motors offer?

Accepted Answer

Variable speed control capability

Answer

Enhanced efficiency

Answer

Lower cost

Answer

Smaller physical size

Question 19

Stepper motors are characterized by which unique feature?

Accepted Answer

Precise angular control

Answer

High torque at low speeds

Answer

Self-starting capability

Answer

High energy efficiency

Question 20

In an AC induction motor, what is the primary role of the stator?

Accepted Answer

Generating a rotating magnetic field

Answer

Converting electrical energy into mechanical energy

Answer

Controlling motor speed

Answer

Providing a path for electrical current

Question 21

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

Accepted Answer

Reversing the current direction in the armature

Answer

Controlling motor speed

Answer

Providing a path for electrical current

Answer

Generating a rotating magnetic field

Question 22

What is the primary function of a centrifugal switch in an AC induction motor?

Accepted Answer

Disconnects the starting winding when the motor reaches a certain speed

Answer

Protects the motor from overloads

Answer

Controls the direction of rotation

Answer

Provides a starting torque for the motor

Question 23

Which type of motor finds applications in precision control systems like robotics?

Accepted Answer

Stepper motor

Answer

AC motor

Answer

DC motor

Question 24

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

Accepted Answer

Reverses the direction of current flow

Answer

Regulates the speed of the motor

Answer

Converts AC to DC

Question 25

Which type of AC motor is commonly used in household appliances?

Accepted Answer

Induction motor

Answer

Synchronous motor

Answer

Brushless DC motor

Question 26

Which type of motor is used in high-performance vehicles?

Accepted Answer

Brushless DC motor

Answer

AC induction motor

Answer

Stepper motor

Question 27

The resolver in a stepper motor provides:

Accepted Answer

Feedback on the motor's position

Answer

Conversion of electrical energy into mechanical energy

Answer

Storage of energy for the motor

Question 28

What force creates the turning power, or torque, in a DC motor?

Accepted Answer

Magnetic force

Answer

Gravitational force

Answer

Electrostatic force

Answer

Centrifugal force

Question 29

Which factor has the most direct influence on the speed of an AC motor?

Accepted Answer

Frequency of the AC power supply

Answer

Voltage of the AC power supply

Answer

Current drawn by the motor

Answer

Load on the motor shaft

Question 30

For applications needing strong starting power at slow speeds, like elevators and cranes, which motor type is best?

Accepted Answer

DC motor

Answer

AC motor

Answer

Stepper motor

Question 31

Which among the following is not a type of electrical motor?

Accepted Answer

Combustion engine

Answer

AC motor

Answer

DC motor

Answer

Stepper motor

Question 32

The operating principle of an AC motor is based on:

Accepted Answer

Electromagnetic induction

Answer

Commutation

Answer

Permanent magnetism

Answer

Thermal expansion

Question 33

Permanent magnets create the magnetic field in which type of DC motor?

Accepted Answer

Permanent magnet motor

Answer

Shunt motor

Answer

Series motor

Answer

Compound motor

Question 34

A characteristic of stepper motors is their:

Accepted Answer

Precise angular control

Answer

High speed

Answer

Continuous rotation

Answer

High torque

Question 35

A component found in a DC motor but not in an AC motor is the:

Accepted Answer

Commutator

Answer

Rotor

Answer

Stator

Answer

Capacitor

Question 36

Which of these is not a type of electrical motor?

Accepted Answer

Hydraulic motor

Answer

AC motor

Answer

DC motor

Question 37

Which type of motor is commonly used in cordless power tools due to its portability and compact size?

Accepted Answer

DC motor

Answer

Synchronous motor

Answer

Stepper motor

Answer

AC motor

Question 38

The primary advantage of an AC motor lies in its:

Accepted Answer

High efficiency and reliability

Answer

Compact size and lightweight

Answer

High torque and speed

Answer

Low cost and maintenance

Question 39

Which type of motor is widely used in industrial machinery applications, where high torque and efficiency are crucial?

Accepted Answer

Induction motor

Answer

Universal motor

Answer

Commutator motor

Answer

Brushless motor

Question 40

What is the key difference between a synchronous motor and an asynchronous motor?

Accepted Answer

Synchronous motors operate at a constant speed, while asynchronous motors experience a slight slip at speeds below synchronous speed.

Answer

Synchronous motors have higher torque than asynchronous motors.

Question 41

In computer hard drives, which type of motor is utilized for precise movement and positioning?

Accepted Answer

Stepper motor

Answer

Synchronous motor

Answer

AC motor

Answer

DC motor

Question 42

The primary function of a commutator in a DC motor is to:

Accepted Answer

Reverse the direction of current flow in the armature every half cycle, enabling continuous rotation.

Answer

Regulate the voltage supplied to the armature

Question 43

The primary advantage of a brushless DC motor over a brushed DC motor is:

Accepted Answer

Elimination of mechanical wear and tear on the commutator, resulting in extended lifespan and reduced maintenance requirements.

Answer

Higher efficiency and torque

Answer

Lower noise and vibration

Question 44

Which type of motor is commonly found in washing machines, where variable speed and reversible operation are required?

Accepted Answer

Universal motor

Answer

Stepper motor

Answer

Induction motor

Question 45

The principle of operation of a stepper motor involves:

Accepted Answer

Energizing different stator coils in sequence, causing the motor to rotate in discrete steps.

Answer

Using a magnetic field to induce current in the rotor, creating rotation.

Answer

Using a rotating magnetic field to induce current in the stator, creating rotation.

Question 46

Which advantage is a primary benefit of a brushless DC motor over a brushed DC motor?

Accepted Answer

Reduced wear and tear as it lacks brushes

Answer

Lower manufacturing cost

Answer

Higher efficiency at all operating speeds

Question 47

For precision positioning systems used in robotics and CNC machines, which motor type is commonly employed?

Accepted Answer

Stepper Motor

Answer

Universal Motor

Answer

Induction Motor

Answer

DC Shunt Motor

Question 48

In a DC shunt motor, when field current decreases while armature voltage remains constant, what happens to its speed?

Accepted Answer

Speed increases

Answer

Speed remains the same

Answer

Speed decreases

Answer

Motor stops

Question 49

Clocks and timers often utilize motors that operate at a consistent speed. Which motor type is suitable for such applications?

Accepted Answer

Synchronous Motor

Answer

DC Compound Motor

Answer

Universal Motor

Answer

Stepper Motor

Question 50

In a DC motor, what is the primary purpose of a commutator?

Accepted Answer

To reverse the current direction in the armature windings

Answer

To control the speed of the motor

Answer

To start and stop the motor

Question 51

What is the main function of a motor starter?

Accepted Answer

To limit the current drawn by the motor during start-up

Answer

To convert AC power to DC power

Answer

To protect the motor from overloads

Answer

To regulate the speed of the motor

Question 52

In an induction motor, what does the term 'slip' refer to?

Accepted Answer

The difference in speed between the rotating magnetic field and the rotor

Answer

The amount of torque produced by the motor

Answer

The efficiency of the motor