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Electrical Machines Multiple-Choice Questions (MCQs)

Electrical Machines is a subject of Electrical Engineering specially in Electrical and Power engineering programs. Electrical Machines is all about the study of designing electrical machines like motors, generators, transformers, etc.

Electrical Machines MCQs: Explore and practice these top 100+ multiple-choice questions with answers on all chapters of Electrical Machines to test and enhance your knowledge of Electrical Machines. These Electrical Machines MCQs are helpful to prepare for your exams, Gate preparation, Interviews, and other related exams. Each question has the answers with their explanations for your understanding.

Electrical Machines MCQs with Answers

1. An ____ is a mechanism that transforms electrical energy into various types of energy.

  1. Electromagnetic machine
  2. Electrical flux
  3. Electrical machine
  4. Electrical signaling

Answer: C) Electrical machine

Explanation:

An Electrical Machine is a mechanism that transforms electrical energy into various types of energy.

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2. What are electromechanical energy conversion devices?

  1. An electromechanical energy conversion device is a device that converts electrical energy into mechanical energy but not vice versa
  2. An electromechanical energy conversion device is a device that converts mechanical energy into electrical energy but not vice versa
  3. An electromechanical energy conversion device is a device that converts electrical energy into mechanical energy and vice versa

Answer: C) An electromechanical energy conversion device is a device that converts electrical energy into mechanical energy and vice versa.

Explanation:

An electromechanical energy conversion device is a device that converts electrical energy into mechanical energy or mechanical energy into electrical energy.

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3. Is an electric generator an example of an electromechanical energy conversion device?

  1. No
  2. Yes

Answer: B) Yes

Explanation:

Yes, an electric generator is an example of an electromechanical energy conversion device.

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4. Any electromechanical energy conversion device uses which of the following field to convert electrical energy into mechanical energy and vice versa?

  1. Electric field
  2. Magnetic field
  3. Both

Answer: C) Both

Explanation:

Any electromechanical energy conversion device uses an electric or magnetic field to convert electrical energy into mechanical energy and vice versa.

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5. How many types of electromechanical energy conversion devices are there?

  1. 5
  2. 4
  3. 3
  4. 2

Answer: D) 2

Explanation:

There are two types of electromechanical energy conversion devices:

  • Gross motion devices
  • Incremental motion devices

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6. Escalators are examples of which type of electromechanical energy conversion devices?

  1. Gross motion devices
  2. Incremental motion devices
  3. Both

Answer: A) Gross motion devices

Explanation:

Escalators are examples of gross motion devices type.

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7. Which of the following is not an example of an Incremental motion device?

  1. Linear actuators
  2. Encoders
  3. Roller coasters
  4. Vernier scales

Answer: C) Roller coasters

Explanation:

Except for roller coasters, all other elements are examples of incremental motion devices.

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8. What is an electric motor?

  1. The electric motor is a device that transforms electrical energy into mechanical energy and vice versa
  2. The electric motor is a device that transforms mechanical energy into electrical energy
  3. The electric motor is a device that transforms electrical energy into mechanical energy

Answer: C) The electric motor is a device that transforms electrical energy into mechanical energy.

Explanation:

The electric motor is a device that transforms electrical energy into mechanical energy.

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9. What is an electric generator?

  1. The electric generator is a device that transforms mechanical energy into electrical energy and vice versa
  2. The electric generator is a device that transforms mechanical energy into electrical energy
  3. The electric generator is a device that transforms electrical energy into mechanical energy

Answer: B) The electric generator is a device that transforms mechanical energy into electrical energy.

Explanation:

The electric generator is a device that transforms mechanical energy into electrical energy.

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10. The total input energy in an electromechanical energy conversion device is equal to the ____.

  1. Sum of three components (Energy dissipated or lost, Energy stored, Useful output, energy)
  2. Product of three components (Energy dissipated or lost, Energy stored, Useful output, energy)
  3. Difference of three components (Energy dissipated or lost, Energy stored, Useful output, energy)

Answer: A) Sum of three components (Energy dissipated or lost, Energy stored, Useful output, energy)

Explanation:

The total input energy in an electromechanical energy conversion device is equal to the sum of three components (Energy dissipated or lost, Energy stored, Useful output, and energy).

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11. Which of the following is the process of giving electrical input to an electromechanical energy conversion device?

  1. Coenergy
  2. Excitation
  3. Flux

Answer: B) Excitation

Explanation:

Excitation is the process of giving electrical input to an electromechanical energy conversion device.

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12. Electromechanical energy conversion systems are categorized into how many types based on the number of electrical inputs?

  1. 5
  2. 4
  3. 3
  4. 2

Answer: D) 2

Explanation:

Electromechanical energy conversion systems are categorized into two kinds based on the number of electrical inputs:

  • Singly-Excited System
  • Doubly-Excited System

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13. How many electrical inputs are required for the singly excited system?

  1. More than 1
  2. 1
  3. 0

Answer: B) 1

Explanation:

A single electrical input is required for the singly excited system.

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14. Which of the following is TRUE about a doubly-excited system?

  1. A doubly-excited system needs two integrated electrical inputs
  2. A doubly-excited system needs any number of integrated electrical inputs
  3. A doubly-excited system needs two distinct electrical inputs

Answer: C) A doubly-excited system needs two distinct electrical inputs.

Explanation:

A doubly-excited system needs two distinct electrical inputs.

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15. A rotating electrical machine is made up of how many major components?

  1. 5
  2. 4
  3. 3
  4. 2

Answer: D) 2

Explanation:

A rotating electrical machine is made up of two major components.

  • Stator
  • Rotor

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16. Which of the following is TRUE about the stator and rotor?

  1. The stator and rotor are not separated i.e., means they are integrated
  2. The stator and rotor are separated by magnetic flux
  3. The stator and rotor are separated by electric flux
  4. The stator and rotor are separated by an air gap

Answer: D) The stator and rotor are separated by an air gap

Explanation:

The stator and rotor are separated by an air gap.

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17. Which of the following is the stationary part in the rotating electrical machine?

  1. Stator
  2. Rotor
  3. Both
  4. None, both remain in motion always

Answer: A) Stator

Explanation:

Stator is the stationary part of the rotating electrical machine.

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18. What do you mean by armature winding?

  1. The winding of a machine that induces current is known as armature winding
  2. The winding of a machine that induces voltage is known as armature winding
  3. The winding of a machine that induces flux is known as armature winding
  4. The winding of a machine that induces magnetic flux is known as armature winding

Answer: B) The winding of a machine that induces voltage is known as armature winding.

Explanation:

The winding of a machine that induces voltage is known as armature winding.

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19. What do you mean by field winding?

  1. Field winding refers to the winding that produces the machine's primary working electric flux
  2. Field winding refers to the winding that produces the machine's primary working magnetic flux

Answer: B) Field winding refers to the winding that produces the machine's primary working magnetic flux.

Explanation:

Field winding refers to the winding that produces the machine's primary working magnetic flux.

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20. What is the full form of RMF?

  1. Rotor magnetic flux
  2. Rotor magnetic flux
  3. Rotating mechanical field
  4. Rotating magnetic field

Answer: D) Rotating magnetic field

Explanation:

RMF stands for rotating magnetic field.

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21. What do you mean by RMF?

  1. Electrical fields that rotate or change direction over time are referred to as rotating magnetic fields
  2. Mechanical fields that rotate or change direction over time are referred to as rotating mechanical fields
  3. Magnetic fields that rotate or change direction over time are referred to as rotating magnetic fields

Answer: C) Magnetic fields that rotate or change direction over time are referred to as rotating magnetic fields

Explanation:

Magnetic fields that rotate or change direction over time are referred to as rotating magnetic fields.

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22. The speed at which the magnetic field rotates is known as the ____ speed.

  1. Synchronous speed
  2. Asynchronous speed

Answer: A) Synchronous speed

Explanation:

The speed at which the magnetic field rotates is known as the synchronous speed.

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23. Synchronous speed is measured in ____.

  1. Radian per second
  2. Revolution per minute
  3. Degree
  4. Delta

Answer: B) Revolution per minute

Explanation:

Synchronous speed is measured in Revolution per minute.

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24. The ____ is the primary force that causes the machine's rotor to revolve.

  1. Moment
  2. Speed
  3. Linear momentum
  4. Torque

Answer: D) Torque

Explanation:

The torque is the primary force that causes the machine's rotor to revolve.

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25. In electromagnetic devices how many types of torques are developed?

  1. 2
  2. 3
  3. 6
  4. 8

Answer: A) 2

Explanation:

Torques of two sorts are generated in electromagnetic devices:

  • Electromagnetic Torque
  • Reluctance Torque

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26. What is the other name for electromagnetic torque?

  1. Vector torque
  2. Induced torque
  3. Induced flux torque
  4. Non-vector torque

Answer: B) Induced torque

Explanation:

Electromagnetic torque is also known as induced torque.

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27. An EMF is formed in a coil when a changing magnetic field is linked to it; this phenomenon is known as ____.

  1. electromagnetic torque
  2. Reluctance torque
  3. Electromagnetic induction
  4. Electromagnetism (EMF)

Answer: C) Electromagnetic induction

Explanation:

An EMF is formed in a coil when a changing magnetic field is linked to it; this phenomenon is known as electromagnetic induction.

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28. Which law states that An EMF is induced in a conductor or coil when a magnetic flux linking to it changes?

  1. Ohm's law
  2. Ampere's circuital law
  3. Faraday's second law of electromagnetic induction
  4. Faraday's first law of electromagnetic induction

Answer: D) Faraday's first law of electromagnetic induction

Explanation:

faraday's first law of electromagnetic induction states that An EMF is induced in a conductor or coil when a magnetic flux linking to it changes.

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29. What is Faraday's second law of electromagnetic induction?

  1. A conductor or coil's induced EMF is directly proportional to the rate at which electric flux linkages are changing with torque
  2. A conductor or coil's induced EMF is directly proportional to the rate at which magnetic flux linkages are changing with time
  3. A conductor or coil's induced EMF is directly proportional to the rate at which electric flux linkages are changing with speed

Answer: C) A conductor or coil's induced EMF is directly proportional to the rate at which electric flux linkages are changing with speed.

Explanation:

Faraday's second law of electromagnetic induction states that: A coil's induced EMF is directly proportional to the rate at which magnetic flux linkages are changing with time.

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30. According to which law, when an induced current arises in a conductor, the direction of the current opposes the change in the magnetic field that caused it?

  1. Ohm's Law
  2. Ampere's circuital Law
  3. Gauss's Law
  4. Lenz's Law

Answer: D) Lenz's Law

Explanation:

According to Lenz's Law, when an induced current arises in a conductor, the direction of the current opposes the change in the magnetic field that caused it.

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31. The EMF created in AC and DC generators is an example of ____.

  1. Dynamically induced EMF
  2. Statically induced EMF

Answer: A) Dynamically induced EMF

Explanation:

The EMF created in AC and DC generators is an example of dynamically induced EMF.

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32. How many types of induced EMFs are there?

  1. 5
  2. 4
  3. 2
  4. 6

Answer: C) 2

Explanation:

There are two types of induced EMF:

  • Dynamically induced EMF
  • Statically induced EMF

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33. Which of the following is TRUE about Dynamically induced EMF?

  1. Dynamically induced EMF occurs when a moving conductor or coil is put in a stationary electric field
  2. Dynamically induced EMF occurs when a moving conductor or coil is put in a rotatory magnetic field
  3. Dynamically induced EMF occurs when a moving conductor or coil is put in a stationary magnetic field

Answer: C) Dynamically induced EMF occurs when a moving conductor or coil is put in a stationary magnetic field.

Explanation:

Dynamically induced EMF occurs when a moving conductor or coil is put in a stationary magnetic field.

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34. The EMF produced in a transformer is an example of ____ EMF.

  1. Dynamically induced EMF
  2. Statically induced EMF

Answer: B) Statically induced EMF

Explanation:

The EMF produced in a transformer is an example of statically induced EMF.

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35. How many types of statically induced EMF are there?

  1. 5
  2. 2
  3. 4
  4. 3

Answer: B) 2

Explanation:

The statically induced EMF is further categorized into two categories:

  • Self-Induced EMF
  • Mutually Induced EMF

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36. What do you mean by Self-induced EMF?

  1. Self-induced EMF occurs when an EMF is generated in a conductor or coil as a result of a change in its electric flux linkage
  2. Self-induced EMF occurs when an EMF is generated in a conductor or coil as a result of a change in its electromagnetic flux linkage
  3. Self-induced EMF occurs when an EMF is generated in a conductor or coil as a result of a change in its magnetic flux linkage

Answer: C) Self-induced EMF occurs when an EMF is generated in a conductor or coil as a result of a change in its magnetic flux linkage.

Explanation:

Self-induced EMF occurs when an EMF is generated in a conductor or coil as a result of a change in its magnetic flux linkage.

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37. What do you mean by mutually induced EMF?

  1. A mutually induced EMF refers to the EMF generated in a coil as a result of a neighboring coil's changing electric field
  2. A mutually induced EMF refers to the EMF generated in a coil as a result of a neighboring coil's changing magnetic field
  3. A mutually induced EMF refers to the EMF generated in a coil as a result of a neighboring coil's stationary magnetic field
  4. A mutually induced EMF refers to the EMF generated in a coil as a result of a neighboring coil's stationary electric field

Answer: B) A mutually induced EMF refers to the EMF generated in a coil as a result of a neighboring coil's changing magnetic field.

Explanation:

A mutually induced EMF refers to the EMF generated in a coil as a result of a neighboring coil's changing magnetic field.

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38. Which of the following principle posits that an EMF is produced in a conductor when it is subjected to relative motion with a magnetic field?

  1. Superposition principle
  2. Principle of electromagnetic induction
  3. Ohm's Law
  4. Maxwell's magnetic principle

Answer: B) Principle of electromagnetic induction

Explanation:

The principle of electromagnetic induction posits that an EMF is produced in a conductor when it is subjected to relative motion with a magnetic field.

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39. For finding the direction of the force on an electrical conductor in a magnetic field, Fleming's Which hand rule is particularly useful?

  1. Fleming's left-hand rule
  2. Fleming's right-hand rule

Answer: A) Fleming's left-hand rule

Explanation:

For finding the direction of the force on an electrical conductor in a magnetic field, Fleming's left-hand rule is particularly useful.

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40. Fleming's which hand rule is applied to electric generators?

  1. Fleming's left-hand rule
  2. Fleming's right-hand rule

Answer: B) Fleming's right-hand rule

Explanation:

The right-hand rule of Fleming applies to electric generators.

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41. What are Electrical transformers?

  1. Electrical transformers are dynamic AC machines that change the level of alternating current
  2. Electrical transformers are static DC machines that change the level of alternating current
  3. Electrical transformers are static AC machines that change the level of alternating current

Answer: C) Electrical transformers are static AC machines that change the level of alternating current.

Explanation:

Electrical transformers are static AC machines that change the level of alternating current.

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42. How many types of windings are present in a transformer?

  1. 5
  2. 3
  3. 6
  4. 2

Answer: D) 2

Explanation:

Two types of windings are present in the transformer:

  • Primary winding
  • Secondary winding

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43. The operation of a transformer is based on which of the following?

  1. Principle of electromagnetic induction
  2. Principle of electromagnetic admittance
  3. Principle of electromagnetic reluctance

Answer: A) Principle of electromagnetic induction.

Explanation:

The operation of a transformer is based on the principle of electromagnetic induction.

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44. What is a set-up transformer?

  1. When the transformer's output voltage exceeds the input voltage, the transformer is referred to as a set-up transformer
  2. When the transformer's output voltage lags behind the input voltage, the transformer is referred to as a set-up transformer
  3. When the transformer's output voltage is equal to the input voltage, the transformer is referred to as a set-up transformer

Answer: A) When the transformer's output voltage exceeds the input voltage, the transformer is referred to as a set-up transformer.

Explanation:

When the transformer's output voltage exceeds the input voltage, the transformer is referred to as a set-up transformer.

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45. What is a set-down transformer?

  1. When the transformer's output voltage exceeds the input voltage, the transformer is referred to as a set-down transformer
  2. When the transformer's output voltage lags behind the input voltage, the transformer is referred to as a set-down transformer
  3. When the transformer's output voltage is equal to the input voltage, the transformer is referred to as a set-down transformer

Answer: B) When the transformer's output voltage lags behind the input voltage, the transformer is referred to as a set-down transformer.

Explanation:

When the transformer's output voltage lags behind the input voltage, the transformer is referred to as a set-down transformer.

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46. Can we operate the transformer on direct current?

  1. Yes
  2. No

Answer: B) No

Explanation:

Because a transformer is an electromagnetic induction mechanism, it cannot operate on direct current.

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47. A transformer consists of how many basic parts?

  1. 5
  2. 4
  3. 3
  4. 9

Answer: C) 3

Explanation:

A transformer is made up of three key components: a primary winding, a secondary winding, and a magnetic core.

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48. Which of the following key component of a transformer is responsible to take the output?

  1. A primary winding
  2. A secondary winding
  3. A magnetic core

Answer: B) A secondary winding

Explanation:

The secondary winding component of a transformer is responsible to take the output.

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49. The transformer's core is built of ____.

  1. Silicon steel
  2. Copper
  3. Aluminium
  4. Bronze

Answer: A) Silicon steel

Explanation:

The transformer's core is built of high-quality silicon steel.

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50. Which type of construction is best suited for low-voltage transformers?

  1. Shell-type transformer
  2. Core-type transformer

Answer: A) Shell-type transformer

Explanation:

Because of the poor nature of cooling caused by the embedding of the windings, the shell-type construction is better suited for low-voltage transformers.

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51. The ____ of a transformer is the ratio of the number of turns in the primary winding to the number of turns in the secondary winding.

  1. Turn frequency
  2. Voltage transformer ratio
  3. Transformer ratio
  4. Turn ratio

Answer: D) Turn ratio

Explanation:

The turns ratio of a transformer is the ratio of the number of turns in the primary winding to the number of turns in the secondary winding.

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52. ____ is the ratio of the output voltage to an input voltage of a transformer.

  1. Turn frequency
  2. Voltage transformer ratio
  3. Transformer ratio
  4. Turn ratio

Answer: B) Voltage transformer ratio

Explanation:

Voltage transformer ratio is the ratio of output voltage to input voltage of a transformer.

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53. The resistance of the primary and secondary windings in an ideal transformer is equal to ____.

  1. Infinite
  2. 1
  3. 0
  4. Negative
  5. Finite

Answer: C) 0

Explanation:

The resistance of the primary and secondary windings in an ideal transformer is equal to 0 or negligible.

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54. There is a ____ resistance between the primary and secondary windings in a practical transformer.

  1. Infinite
  2. 1
  3. 0
  4. Negative
  5. Finite

Answer: E) Finite

Explanation:

There is a finite resistance between the primary and secondary windings.

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55. The flow of alternating magnetic flux causes which loss in the transformer's magnetic core?

  1. Iron Loss
  2. Copper Loss
  3. Stray Loss
  4. Dielectric Loss

Answer: A) Iron Loss

Explanation:

The flow of alternating magnetic flux causes iron loss in the transformer's magnetic core.

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56. Which of the following test is used on transformers to evaluate the iron or core loss?

  1. open-circuit test
  2. Short-circuit test

Answer: A) open-circuit test

Explanation:

The open-circuit test is used on transformers to evaluate iron or core loss.

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57. Which of the following test is performed on the transformer to ascertain the value of its copper loss?

  1. open-circuit test
  2. Short-circuit test

Answer: B) Short-circuit test

Explanation:

We perform a "short-circuit test" on the transformer to ascertain the value of its copper loss.

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58. Which of the following statement is TRUE?

  1. The copper loss in a transformer, changes with the cube of the load current
  2. The copper loss in a transformer, changes exponentially with the load current
  3. The copper loss in a transformer, changes with the square of the load current

Answer: C) The copper loss in a transformer, changes with the square of the load current.

Explanation:

The copper loss in a transformer, changes with the square of the load current.

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59. A portion of the overall flux follows a path through the air, and this flux is known as ____.

  1. Dielectric flux
  2. Magnetic flux
  3. Total flux
  4. Leakage flux

Answer: D) Leakage flux

Explanation:

A portion of the overall flux follows a path through the air, and this flux is known as leakage flux.

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60. ____ loss is the power loss that happens in insulating materials such as oil, solid insulation of the transformer, and so on.

  1. Iron Loss
  2. Copper Loss
  3. Stray Loss
  4. Dielectric Loss

Answer: D) Dielectric Loss

Explanation:

Dielectric loss is the power loss that happens in insulating materials such as oil, solid insulation of the transformer, and so on.

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61. How do we represent transformer efficiency?

  1. Delta
  2. Gamma
  3. Eta (η)
  4. Zeta

Answer: C) Eta (η)

Explanation:

The transformer efficiency is represented by the Greek letter Eta (η).

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62. The windings of a three-phase transformer may be connected in how many ways?

  1. 5
  2. 4
  3. 6
  4. 2

Answer: B) 4

Explanation:

The windings of a three-phase transformer may be connected in four different ways:

  • Star-Star Connection
  • Delta-Delta Connection
  • Delta-Star Connection
  • Star-Delta Connection

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63. Transformers are categorized into how many categories based on the number of turns in the primary and secondary windings?

  1. 5
  2. 4
  3. 3
  4. 7

Answer: C) 3

Explanation:

Transformers are categorized into three categories based on the number of turns in the primary and secondary windings:

  • Step-up transformer
  • Step-down transformer
  • One-to-one transformer

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64. Transformers may be classified into how many major categories based on their application?

  1. 2
  2. 3
  3. 4
  4. 5

Answer: B) 3

Explanation:

Transformers may be classified into three major categories based on their application:

  • Power transformers
  • Distribution transformers
  • Instrument transformers

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65. A ____ transformer has the same number of turns in both the primary and secondary windings and provides an output voltage equal to the input voltage.

  1. Step-up transformer
  2. Step-down transformer
  3. One-to-one transformer

Answer: C) One-to-one transformer

Explanation:

A one-to-one transformer has the same number of turns in both the primary and secondary windings and provides an output voltage equal to the input voltage.

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66. Instrument transformers are classified into how many kinds based on the sort of amount transformed?

  1. 5
  2. 4
  3. 3
  4. 2

Answer: D) 2

Explanation:

Instrument transformers are classified into two kinds based on the sort of amount transformed:

  • Current Transformer (C.T.)
  • Potential Transformer (P.T.)

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67. A ____ transformer is a sort of instrument transformer that is used to reduce a power line's high alternating current to a quantifiable low value.

  1. Current Transformer (C.T.)
  2. Potential Transformer (P.T.)

Answer: A) Current Transformer (C.T.)

Explanation:

A current transformer is a sort of instrument transformer that is used to reduce a power line's high alternating current to a quantifiable low value.

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68. A potential transformer is a voltage ____ transformer.

  1. Step-up transformer
  2. Step-down transformer
  3. One-to-one transformer

Answer: B) Step-down transformer

Explanation:

A potential transformer is a voltage step-down transformer.

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69. What is a DC machine?

  1. A DC machine is an electromechanical device that can transform direct current (dc) electricity but not vice versa
  2. A DC machine is an electromechanical device that can transform mechanical energy into direct current (dc) electricity but not vice versa
  3. A DC machine is an electromechanical device that can transform direct current (dc) electricity into mechanical energy and vice versa

Answer: C) A DC machine is an electromechanical device that can transform direct current (dc) electricity into mechanical energy and vice versa.

Explanation:

A DC machine is an electromechanical device that can transform direct current (dc) electricity into mechanical energy or mechanical energy into direct current (dc) electricity.

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70. What is a DC motor?

  1. A DC motor is a mechanism that transforms DC electrical energy into mechanical energy
  2. A DC motor is a mechanism that transforms mechanical energy into DC electrical energy

Answer: A) A DC motor is a mechanism that transforms DC electrical energy into mechanical energy.

Explanation:

A DC motor is a mechanism that transforms DC electrical energy into mechanical energy.

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71. What is DC Generator?

  1. A DC Generator is a mechanism that transforms DC electrical energy into mechanical energy
  2. A DC Generator is a mechanism that transforms mechanical energy into DC electrical energy

Answer: B) A DC Generator is a mechanism that transforms mechanical energy into DC electrical energy.

Explanation:

A DC Generator is a mechanism that transforms mechanical energy into DC electrical energy.

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72. Which of the following is the DC machine's exterior frame?

  1. Yoke
  2. Armature
  3. Brushes
  4. Commutator

Answer: A) Yoke

Explanation:

The yoke is the DC machine's exterior frame.

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73. In direct current machines, an ____ is a system of conductors that can freely revolve on the supporting bearings.

  1. Field system
  2. Armature
  3. Brushes
  4. Commutator

Answer: B) Armature

Explanation:

In direct current machines, an armature is a system of conductors that can freely revolve on the supporting bearings.

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74. The yoke of a DC machine is constructed of ____.

  1. Aluminium
  2. Copper
  3. Gold
  4. Steel

Answer: D) Steel

Explanation:

The yoke of a DC machine is constructed of cast steel.

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75. The armature in DC is made up of how many major components?

  1. 5
  2. 4
  3. 3
  4. 2

Answer: D) 2

Explanation:

The armature in DC is made up of two major components: the armature core and the armature winding.

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76. Which of the following make up the armature winding in DC?

  1. Aluminium Wires
  2. Copper wires
  3. Gold wires
  4. Steel wires

Answer: B) Copper wires

Explanation:

Copper wires make up the armature winding in DC.

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77. The field system is a ____ component of a DC machine.

  1. Stationary
  2. Moving

Answer: A) Stationary

Explanation:

The field system is a stationary component of a DC machine.

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78. How many components does a field system in dc machines have?

  1. 5
  2. 4
  3. 3
  4. 8

Answer: C) 3

Explanation:

The pole core, pole shoes, and field coils are the three basic components of a field system in dc machines.

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79. The pole core is constructed from ____.

  1. Thin copper laminations
  2. Copper wires
  3. Aluminium Wires
  4. Thin steel laminations

Answer: D) Thin steel laminations.

Explanation:

The pole core is constructed from thin steel laminations.

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80. Which of the following part in DC is used as a mechanical rectifier?

  1. Armature
  2. Brushes
  3. Commutator
  4. Bearings

Answer: C) Commutator

Explanation:

The commutator part in DC is used as a mechanical rectifier.

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81. Which of the following statement is True?

  1. Bearings are utilized in direct current machines to prevent frictional losses
  2. Brushes are utilized in direct current machines to prevent frictional losses
  3. Commutators are utilized in direct current machines to prevent frictional losses
  4. Armature is utilized in direct current machines to prevent frictional losses

Answer: A) Bearings are utilized in direct current machines to prevent frictional losses.

Explanation:

Bearings are utilized in direct current machines to prevent frictional losses.

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82. Based on the field winding the DC generators are of how many types?

  1. 3
  2. 2
  3. 4
  4. 5

Answer: B) 2

Explanation:

Based on field winding the DC generators are of two types:

  • Separately Excited DC Generators
  • Self-Excited DC Generators

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83. Which of the following is True about a separately excited DC generator?

  1. Separately excited DC generators are machines that transform mechanical energy into electrical energy by creating an electric field with a separate source of direct current (DC)
  2. Separately excited DC generators are machines that transform mechanical energy into electrical energy by creating a magnetic field with a separate source of direct current (DC)
  3. Separately excited DC generators are machines that transform mechanical energy into electrical energy by creating an electromagnetic field with a separate source of direct current (DC)

Answer: B) Separately excited DC generators are machines that transform mechanical energy into electrical energy by creating a magnetic field with a separate source of direct current (DC).

Explanation:

Separately excited DC generators are machines that transform mechanical energy into electrical energy by creating a magnetic field with a separate source of direct current (DC).

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84. Based on how the field winding is linked to the armature, Self-excited DC generators are grouped into how many categories?

  1. 3
  2. 2
  3. 6
  4. 5

Answer: A) 3

Explanation:

Self-excited DC generators are grouped into three variants based on how the field winding is linked to the armature:

  • DC series generator
  • Shunt DC generator
  • Compound direct current generator

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85. What is a Shunt DC generator?

  1. A shunt DC generator has its field winding linked in series with its armature winding such that the generator's terminal voltage is applied across it
  2. A shunt DC generator has its field winding linked in parallel with its armature winding such that the generator's terminal voltage is applied across it

Answer: B) A shunt DC generator has its field winding linked in parallel with its armature winding such that the generator's terminal voltage is applied across it.

Explanation:

A shunt DC generator has its field winding linked in parallel with its armature winding such that the generator's terminal voltage is applied across it.

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86. The compound dc generators are of how many types?

  1. 5
  2. 4
  3. 3
  4. 2

Answer: D) 2

Explanation:

The compound dc generators are further classified into two types:

  • Short-shunt compound direct current generator
  • Long-shunt compound direct current generator

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87. Which of the following compound DC generator has shunt field winding in parallel with series field winding and armature winding?

  1. Short-shunt compound direct current generator
  2. Long-shunt compound direct current generator

Answer: B) Long-shunt compound direct current generator

Explanation:

A long-shunt compound DC generator has shunt field winding in parallel with series field winding and armature winding.

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88. A DC motor's operation is based on which of the following Law?

  1. Law of electromagnetic interaction
  2. Ohm's Law
  3. Gauss Law for electric field
  4. Ampere's Law

Answer: A) Law of electromagnetic interaction

Explanation:

A DC motor's operation is based on the law of electromagnetic interaction.

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89. What is the relationship between the back EMF and the applied voltage?

  1. The back EMF is always greater than the applied voltage
  2. The back EMF is always equal to the applied voltage
  3. The back EMF is always less than the applied voltage

Answer: C) The back EMF is always less than the applied voltage

Explanation:

The back EMF is always less than the applied voltage.

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90. If the speed of the DC motor is high, then the value of back EMF is ____.

  1. Large
  2. Smalls
  3. Zero
  4. No effect

Answer: A) Large

Explanation:

When the speed of the DC motor is high, the value of back EMF is high.

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91. Based on the connection of field winding in the motor circuit DC motors are classified into how many types?

  1. 5
  2. 3
  3. 2
  4. 1

Answer: C) 2

Explanation:

DC motors are categorized into two categories based on the connection of the field winding in the motor circuit:

  • Separately Excited Direct Current Motors
  • Self-Excited Direct Current Motors

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92. A ____ DC motor is one whose magnetic field winding is stimulated by an independent source of DC electric supply.

  1. Separately Excited Direct Current Motors
  2. Self-Excited Direct Current Motors

Answer: A) Separately Excited Direct Current Motors

Explanation:

A separately excited DC motor is one whose magnetic field winding is stimulated by an independent source of DC electric supply.

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93. Self-excited direct current motors are categorized into how many categories based on how the field winding is coupled to the armature winding?

  1. 5
  2. 4
  3. 3
  4. 2

Answer: C) 3

Explanation:

Self-excited direct current motors are categorized into three categories based on how the field winding is coupled to the armature winding:

  • Series DC motor
  • Shunt DC motor
  • Compound DC motor

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94. In DC machines losses are of how many types?

  1. 5
  2. 3
  3. 2
  4. 1

Answer: B) 3

Explanation:

There are three types of losses in DC machines:

  • Copper losses
  • Iron or core losses
  • Mechanical losses

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95. Which loss in a dc machine is the result of resistance in the various windings of the machine?

  1. Copper losses
  2. Iron or core losses
  3. Mechanical losses

Answer: A) Copper losses

Explanation:

A copper loss in a dc machine is the result of resistance in the various windings of the machine.

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96. During the rotation of the armature in the magnetic field, ____ occurs in the core of the armature of a DC machine.

  1. Copper losses
  2. Iron or core losses
  3. Mechanical losses

Answer: B) Iron or core losses

Explanation:

During the rotation of the armature in the magnetic field, iron losses occur in the core of the armature of a DC machine.

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97. How many types of iron losses are there in DC?

  1. 5
  2. 7
  3. 3
  4. 2

Answer: D) 2

Explanation:

There are two types of iron losses in DC:

  • Hysteresis Loss
  • Eddy Current Loss

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98. Which of the following is TRUE?

  1. Iron losses and Copper losses together are known as stray losses
  2. Iron or core losses and mechanical losses together are known as stray losses
  3. Copper losses and mechanical losses together are known as stray losses

Answer: B) Iron or core losses and mechanical losses together are known as stray losses.

Explanation:

Iron or core losses and mechanical losses together are known as stray losses.

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99. Iron loss and mechanical loss comes under which category of loss?

  1. Constant losses
  2. Variable losses

Answer: A) Constant losses

Explanation:

Iron loss and mechanical loss comes under the category of constant losses.

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100. What do you mean by induction motor?

  1. An induction motor is a type of Synchronous DC electric motor that transforms direct current power into mechanical energy
  2. An induction motor is a type of synchronous AC electric motor that transforms alternating current power into mechanical energy
  3. An induction motor is a type of asynchronous DC electric motor that transforms direct current power into mechanical energy
  4. An induction motor is a type of asynchronous AC electric motor that transforms alternating current power into mechanical energy

Answer: D) An induction motor is a type of asynchronous AC electric motor that transforms alternating current power into mechanical energy.

Explanation:

An induction motor is a type of asynchronous AC electric motor that transforms alternating current power into mechanical energy.

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101. An induction motor has how many parts?

  1. 5
  2. 4
  3. 3
  4. 2

Answer: D) 2

Explanation:

An induction motor mainly has 2 parts:

  • Stator
  • Rotor

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102. Induction motors are split into how many categories based on the type of input supply?

  1. 5
  2. 4
  3. 3
  4. 2

Answer: D) 2

Explanation:

Induction motors are split into two categories based on the type of input supply:

  • Single-Phase Induction Motors
  • Three-Phase Induction Motors

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103. Among Single-Phase Induction Motors and Three-Phase Induction Motors which of the following does not have a feature of self-starting?

  1. Single-Phase Induction Motors
  2. Three-Phase Induction Motors

Answer: A) Single-Phase Induction Motors

Explanation:

Among Single-Phase Induction Motors and Three-Phase Induction Motors Single phase induction motors do not have a feature of self-starting.

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104. How many types of Single-Phase Induction Motors are there?

  1. 5
  2. 4
  3. 3
  4. 2

Answer: C) 3

Explanation:

There are three types of Single-Phase Induction Motors:

  • Split-phase induction motor
  • Capacitor-start induction motor
  • Capacitor-start capacitor-run induction motor

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105. How many types of three-Phase Induction Motors are there?

  1. 2
  2. 3
  3. 4
  4. 5

Answer: A) 2

Explanation:

Three-phase induction motors are grouped into two fundamental categories based on the rotor construction:

  • Squirrel-Cage Induction Motor
  • Slip-Ring Induction Motor

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106. A synchronous machine is an ____ machine.

  1. AC (Alternating current)
  2. DC (Direct current)

Answer: A) AC (Alternating current)

Explanation:

A synchronous machine is an alternating current (AC) machine.

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107. Synchronous machines are categorized into how many categories based on their energy conversion?

  1. 5
  2. 4
  3. 3
  4. 2

Answer: D) 2

Explanation:

Synchronous machines are categorized into two categories based on their energy conversion:

  • Synchronous Power Source
  • Motor Synchronous

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108. What is a synchronous alternator?

  1. A synchronous generator or alternator is a synchronous machine that transforms alternating current electricity into mechanical energy
  2. A synchronous generator or alternator is a synchronous machine that transforms mechanical energy into alternating current electricity

Answer: B) A synchronous generator or alternator is a synchronous machine that transforms mechanical energy into alternating current electricity.

Explanation:

A synchronous generator or alternator is a synchronous machine that transforms mechanical energy into alternating current electricity.

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109. What is a Synchronous motor?

  1. A synchronous motor is a synchronous mechanism that transforms alternating current power into mechanical energy
  2. A synchronous motor is a synchronous mechanism that transforms mechanical energy into alternating current power

Answer: A) A synchronous motor is a synchronous mechanism that transforms alternating current power into mechanical energy.

Explanation:

A synchronous motor is a synchronous mechanism that transforms alternating current power into mechanical energy.

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110. A synchronous machine's operation is based on which of the following laws?

  1. Law of electromagnetic interaction
  2. Law of magnetic interlocking
  3. Both
  4. None

Answer: C) Both

Explanation:

A synchronous machine's operation is based on the law of electromagnetic interaction and the law of magnetic interlocking.

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111. The losses that occur in a three-phase alternator may be classified into how many types?

  1. 5
  2. 4
  3. 3
  4. 2

Answer: C) 3

Explanation:

The losses that occur in a three-phase alternator may be classified into four types:

  • Copper losses
  • Iron or core losses
  • Mechanical losses
  • Stray load losses

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112. What do you mean by A three-phase synchronous motor?

  1. A three-phase synchronous motor is a three-phase synchronous machine that transforms three-phase mechanical energy into electromagnetic energy
  2. A three-phase synchronous motor is a three-phase synchronous machine that transforms three-phase electrical energy into mechanical energy

Answer: B) A three-phase synchronous motor is a three-phase synchronous machine that transforms three-phase electrical energy into mechanical energy.

Explanation:

A three-phase synchronous motor is a three-phase synchronous machine that transforms three-phase electrical energy into mechanical energy.

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113. A synchronous motor will not start on its own.

  1. True
  2. False

Answer: A) True

Explanation:

A synchronous motor will not start on its own. A squirrel-cage winding, known as damper winding, is supplied on the rotor to help the motor self-start.

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114. A synchronous motor is a ____.

  1. Singly excited system
  2. Double-exited system

Answer: B) Double-exited system

Explanation:

A synchronous motor is a doubly excited system, meaning it is linked to two electrical systems.

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115. The synchronous motor's mechanical power ____ as the power angle increases.

  1. Decreases
  2. Increases

Answer: B) Increases

Explanation:

The synchronous motor's mechanical power increases as the power angle increases.

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