1 $Fleming's Left Hand Rule is primarily used to find the direction of which of the following?$

A.

Magnetic field around a wire

B.

Induced EMF in a generator

C.

Flux density in a solenoid

D.

Force experienced by a current-carrying conductor in a magnetic field

2 $In Fleming's Right Hand Rule, what does the forefinger represent?$

A.

Direction of Induced EMF

B.

Direction of Magnetic Field

C.

Direction of Current

D.

Direction of Motion

3 $What is the primary working principle of a transformer?$

A.

Static electricity

B.

Mutual induction

C.

Lorentz force

D.

Self-induction

4 $Which of the following quantities remains constant in an ideal transformer?$

A.

Impedance

B.

Voltage

C.

Current

D.

Frequency

5 $If a DC supply is connected to the primary of a transformer, what is the likely outcome?$

A.

The frequency increases

B.

The secondary voltage is double the primary

C.

The transformer windings may burn out

D.

It works as an ideal transformer

6 $The EMF equation of a single-phase transformer is given by which formula?$

A.

B.

C.

D.

7 $What defines the turns ratio () of a transformer?$

A.

B.

C.

D.

8 $In a Step-Up transformer, which of the following conditions is true?$

A.

and

B.

and

C.

and

D.

and

9 $What is the main advantage of an auto-transformer over a two-winding transformer?$

A.

Saving in copper material

B.

Isolation between input and output

C.

Higher frequency operation

D.

Ability to handle DC

10 $Current Transformers (CT) and Potential Transformers (PT) are collectively known as:$

A.

Instrument Transformers

B.

Power Transformers

C.

Auto-transformers

D.

Distribution Transformers

11 $Why must the secondary of a Current Transformer (CT) never be left open while the primary is energized?$

A.

The measurement accuracy increases

B.

It will develop dangerously high voltage across the secondary

C.

The frequency will drop to zero

D.

It will draw zero current

12 $The core of a transformer is laminated to reduce:$

A.

Eddy current loss

B.

Hysteresis loss

C.

Friction loss

D.

Copper loss

13 $Which principle governs the working of a DC generator?$

A.

Self-Induction

B.

Mutual Induction

C.

Dynamically induced EMF

D.

Static Induction

14 $What is the function of the commutator in a DC generator?$

A.

To reduce friction

B.

To convert induced AC to DC output

C.

To cool the armature

D.

To convert DC to AC

15 $The back EMF () in a DC motor is proportional to:$

A.

B.

C.

D.

16 $Which DC motor has the highest starting torque?$

A.

DC Shunt Motor

B.

DC Series Motor

C.

Differential Compound Motor

D.

Cumulative Compound Motor

17 $Why should a DC Series motor never be started without a load?$

A.

It will stall

B.

It will run at dangerously high speed

C.

The torque will be zero

D.

It will draw zero current

18 $A DC Shunt motor is also known as a:$

A.

Constant flux motor

B.

High torque motor

C.

Variable speed motor

D.

Constant current motor

19 $The purpose of a starter in a DC motor is to:$

A.

Increase the starting torque

B.

Reverse the direction

C.

Control the speed

D.

Limit the high starting current

20 $To control the speed of a DC motor above its rated (base) speed, which method is used?$

A.

Armature resistance control

B.

Ward-Leonard method

C.

Field flux control

D.

Voltage control

21 $To reverse the direction of rotation of a DC motor, one must:$

A.

Reverse either the field or the armature terminals

B.

Reverse both the field and armature terminals

C.

Reverse the supply terminals

D.

Reduce the supply voltage

22 $Which motor is best suited for electric traction (trains)?$

A.

Induction Motor

B.

DC Shunt Motor

C.

Synchronous Motor

D.

DC Series Motor

23 $The synchronous speed () of an AC machine is given by:$

A.

B.

C.

D.

24 $What is the working principle of a 3-phase Induction Motor?$

A.

Production of back EMF

B.

Production of Rotating Magnetic Field (RMF)

C.

DC excitation

D.

Commutation

25 $In an induction motor, 'Slip' () is defined as:$

A.

B.

C.

D.

26 $If the slip of an induction motor is zero, the rotor speed is:$

A.

Half of synchronous speed

B.

Infinite

C.

Zero

D.

Equal to synchronous speed

27 $Why can an induction motor never run at synchronous speed?$

A.

Air gap reluctance

B.

Stator impedance

C.

Friction losses

D.

The relative speed would be zero, inducing no rotor current

28 $The frequency of rotor current () in an induction motor running at slip is:$

A.

B.

C.

D.

29 $Which part of a DC machine acts as the mechanical support for the poles?$

A.

Armature

B.

Brush

C.

Commutator

D.

Yoke

30 $A Single Phase Induction Motor is:$

A.

Self-starting

B.

A synchronous motor

C.

DC operated

D.

Not self-starting

31 $How is a single-phase induction motor made self-starting?$

A.

By using DC supply

B.

By using a heavy rotor

C.

By adding an auxiliary winding to create a phase difference

D.

By increasing supply voltage

32 $Which motor is commonly used in ceiling fans?$

A.

DC Series Motor

B.

Universal Motor

C.

Single phase permanent capacitor induction motor

D.

Permanent Magnet Synchronous Motor

33 $In a transformer, electrical energy is transferred from primary to secondary via:$

A.

Air

B.

Electrostatic field

C.

Magnetic Flux

D.

Copper wires directly

34 $A transformer has 200 turns in primary and 400 turns in secondary. If input is 100V, output voltage is:$

A.

200V

B.

400V

C.

50V

D.

100V

35 $Which loss in a transformer is variable and depends on load current?$

A.

Eddy current loss

B.

Copper loss

C.

Iron loss

D.

Hysteresis loss

36 $Fleming's Right Hand Rule is applicable for:$

A.

DC Generator

B.

Transformer

C.

Battery

D.

DC Motor

37 $In a DC machine, the armature winding is placed on the:$

A.

Yoke

B.

Poles

C.

Stator

D.

Rotor

38 $The condition for maximum efficiency in a transformer is:$

A.

Copper Loss = 0

B.

Iron Loss = 0

C.

Copper Loss = Iron Loss

D.

Copper Loss = 2 Iron Loss

39 $Which instrument transformer is connected in series with the line?$

A.

Current Transformer (CT)

B.

Auto-transformer

C.

Distribution Transformer

D.

Potential Transformer (PT)

40 $What is the unit of Mutual Inductance?$

A.

Henry

B.

Farad

C.

Ohm

D.

Tesla

41 $Applications of a DC Shunt Motor include:$

A.

Cranes and Hoists

B.

Heavy construction trucks

C.

Lathe Machines and Centrifugal Pumps

D.

Electric Locomotives

42 $Squirrel cage induction motors are preferred over wound rotor types because:$

A.

They run at synchronous speed

B.

They have higher starting torque

C.

They allow external resistance insertion

D.

They are rugged, cheaper, and require less maintenance

43 $The speed of a 4-pole induction motor connected to a 50Hz supply will be slightly less than:$

A.

1500 RPM

B.

1000 RPM

C.

3000 RPM

D.

1200 RPM

44 $Which method is used for speed control of a DC motor below its base speed?$

A.

Armature Resistance Control

B.

Pole changing

C.

Flux Control

D.

Frequency Control

45 $In a transformer, the primary and secondary voltages are related by:$

A.

B.

C.

D.

46 $A Universal Motor can operate on:$

A.

AC only

B.

Three-phase supply only

C.

DC only

D.

Both AC and DC

47 $The rotating magnetic field in a 3-phase induction motor rotates at:$

A.

Variable speed

B.

Rotor speed

C.

Synchronous speed

D.

Slip speed

48 $What is the function of the brushes in a DC machine?$

A.

To generate magnetic field

B.

To reduce eddy currents

C.

To collect or supply current to the rotating armature

D.

To support the shaft

49 $Which type of transformer is used for welding purposes?$

A.

Current transformer

B.

Step-up transformer

C.

Instrument transformer

D.

Step-down transformer

50 $Ideally, the resistance of the primary and secondary windings of a transformer should be:$

A.

Infinite

B.

Very high

C.

Zero

D.

Equal to load resistance

Unit 3 - Practice Quiz