DC Machines: Interactive Learning Quizzes for Electrical and Electronic Principles

Question 1

What factor does NOT influence the torque generated by a DC motor?

Accepted Answer

Speed of rotation

Answer

Magnetic field strength

Answer

Current flowing through the armature

Answer

Voltage of the power supply

Question 2

What is the role of back EMF in a DC motor?

Accepted Answer

Opposes the applied voltage

Answer

Increases the current in the armature

Answer

Reduces the speed of rotation

Answer

Reverses the direction of rotation

Question 3

What is the function of a starter within a DC motor circuit?

Accepted Answer

To limit the starting current

Answer

To protect the motor from overload

Answer

To regulate the motor speed

Answer

To reverse the direction of rotation

Question 4

Describe the impact of increasing the field current in a DC generator.

Accepted Answer

Increased terminal voltage

Answer

Decreased terminal voltage

Answer

No change in terminal voltage

Answer

Voltage reversal

Question 5

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

Accepted Answer

Reverse current flow in the armature

Answer

Regulate motor speed

Answer

Generate a magnetic field

Answer

Store energy

Question 6

Which DC motor type provides high starting torque and is often used in cranes and elevators?

Accepted Answer

Series motor

Answer

Shunt motor

Answer

Compound motor

Answer

Permanent magnet motor

Question 7

How is the speed of a DC motor related to the applied voltage?

Accepted Answer

Directly proportional

Answer

Inversely proportional

Answer

Constant

Answer

No relationship

Question 8

How is the generated voltage of a DC generator related to its speed?

Accepted Answer

Directly proportional

Answer

Inversely proportional

Answer

Constant

Answer

No relationship

Question 9

Which factor primarily determines the rotational speed of a DC motor?

Accepted Answer

Voltage applied

Answer

Current in the field

Answer

Torque applied to the load

Answer

Resistance of the armature

Question 10

Which of the following is NOT a component found in a DC motor?

Accepted Answer

Capacitor

Answer

Field windings

Answer

Commutator

Answer

Armature

Question 11

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

Accepted Answer

To reverse the direction of current flow in the armature windings

Answer

To store electrical energy

Answer

To provide mechanical support to the armature

Question 12

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

Accepted Answer

To establish electrical contact between the commutator and the external circuit

Answer

To generate the magnetic field

Answer

To regulate the speed of the motor

Question 13

Which of the following is NOT a type of DC generator?

Accepted Answer

Synchronous generator

Answer

Shunt generator

Answer

Series generator

Answer

Compound generator

Question 14

What is the relationship between the field current and the output voltage of a shunt-wound DC generator?

Accepted Answer

Directly proportional

Answer

Inversely proportional

Answer

No relationship

Answer

Quadratic relationship

Question 15

What is the main purpose of a field rheostat in a DC generator?

Accepted Answer

To control the field current

Answer

To protect the generator from overloads

Answer

To improve the efficiency of the generator

Answer

To regulate the output voltage

Question 16

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

Accepted Answer

To stop or slow down the motor

Answer

To improve the efficiency of the motor

Answer

To reverse the direction of rotation

Answer

To protect the motor from overloads

Question 17

Which of the following is NOT a part of a DC motor construction?

Accepted Answer

Permanent magnet stator

Answer

Commutator

Answer

Armature

Answer

Field winding

Question 18

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

Accepted Answer

Reverses current direction in armature coils

Answer

Provides electrical connection to armature

Answer

Generates magnetic field

Answer

Controls motor speed

Question 19

Which type of DC motor has the highest starting torque?

Accepted Answer

Series wound

Answer

Permanent magnet

Answer

Shunt wound

Answer

Compound wound

Question 20

What is the formula for calculating torque in a DC motor?

Accepted Answer

T = K * I * Φ

Answer

T = V * I / R

Answer

T = K * V * Φ

Answer

T = V * I * Φ

Question 21

What is the purpose of a field winding in a DC generator?

Accepted Answer

To create a magnetic field

Answer

To regulate current flow

Answer

To connect armature coils

Answer

To reduce sparking

Question 22

Which of the following is NOT a type of DC generator?

Accepted Answer

Induction generator

Answer

Separately excited generator

Answer

Self-excited generator

Answer

Permanent magnet generator

Question 23

What is the relationship between the speed of a DC generator and its generated voltage?

Accepted Answer

Directly proportional

Answer

Constant

Answer

Inversely proportional

Answer

Exponential

Question 24

Which of the following factors affects the efficiency of a DC machine?

Accepted Answer

All of the options

Answer

Iron losses

Answer

Copper losses

Answer

Friction and windage losses

Question 25

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

Accepted Answer

To limit starting current

Answer

To reverse motor direction

Answer

To protect motor from overloads

Answer

To increase starting torque