Home » Electrical Engineering » Electrical Engineering MCQ » Electromagnetic induction

Electromagnetic induction MCQ

Electromagnetic induction MCQ Question and Answer

1.The property of coil by which a counter EMF is induced in it. when the current through the coil changes is known as

  • ASelf-inductance
  • BMutual inductance
  • CSeries aiding inductance
  • DCapacitance
Answer / Hint Save Question Comment On Question
Correct Answer : (A)

Self-inductance

Explanation:

The property of coil by which a counter EMF is induced in it. when the current through the coil changes is known as Self-inductance.

2.As per faraday?s law of electromagnetic induction, an EMF is induced in a conductor whenever it

  • ALies perpendicular to magnetic flux
  • BLies in a magnetic line
  • CCuts the magnetic flux
  • DMoves parallel to the direction of the magnetic field
Answer / Hint Save Question Comment On Question
Correct Answer : (C)

Cuts the magnetic flux

Explanation:

As per faraday?s law of electromagnetic induction, an EMF is induced in a conductor whenever it Cuts the magnetic flux.

3.Which of the following circuit elements stores energy in the electromagnetic field?

  • AInductance
  • BCondenser
  • CVariable resistor
  • DResistance
Answer / Hint Save Question Comment On Question
Correct Answer : (A)

Inductance

Explanation:

Inductance stores energy in the electromagnetic field.

4.The inductance of a coil will increase under all the following conditions excepts

  • AWhen more length for the same number of turns is provided
  • BWhen the number of turns of the coil increase
  • CWhen more area for each turn is provided
  • DWhen permeability of the core increases
Answer / Hint Save Question Comment On Question
Correct Answer : (A)

When more length for the same number of turns is provided

Explanation:

The inductance of a coil will increase under all the following conditions excepts When more length for the same number of turns is provided.

5.Higher the self-inductance of the coil

  • ALesser its Webber-turns
  • BLower the e.m.f induced
  • CGreater the flux produced by it
  • DLonger the delay in establishing steady current through it
Answer / Hint Save Question Comment On Question
Correct Answer : (D)

Longer the delay in establishing steady current through it

Explanation:

Higher the self-inductance of the coil Longer the delay in establishing steady current through it.

6.In an iron cored coil the iron core is removed so that the coil becomes an air cored coil. The inductance of the coil will

  • AIncrease
  • BDecrease
  • CRemain same
  • DInitially increase then decrease
Answer / Hint Save Question Comment On Question
Correct Answer : (B)

Decrease

Explanation:

In an iron cored coil the iron core is removed so that the coil becomes an air cored coil. The inductance of the coil will Decrease.

7.An open coil has

  • AZero resistance and inductance
  • BInfinite resistance and Zero inductance
  • CInfinite resistance and normal inductance
  • DZero resistance and high inductance 
Answer / Hint Save Question Comment On Question
Correct Answer : (B)

Infinite resistance and Zero inductance

Explanation:

An open coil has Infinite resistance and Zero inductance.

8.Both the number of turn and core length of an inductive coil are doubled. Its self-inductance will be

  • AUnaffected
  • BDoubled
  • CHalved
  • DQuadrupled
Answer / Hint Save Question Comment On Question
Correct Answer : (B)

Doubled

Explanation:

Both the number of turn and core length of an inductive coil are doubled. Its self-inductance will be Doubled.

9.If current in a conductor increases then according to Lenz?s law self-inductance voltage will

  • AAid the increasing current
  • BTends to decrease the amount of current
  • CProduce current opposite to the increasing current
  • DAid the applied voltage
Answer / Hint Save Question Comment On Question
Correct Answer : (C)

Produce current opposite to the increasing current

Explanation:

If current in a conductor increases then according to Lenz?s law self-inductance voltage will Produce current opposite to the increasing current.

10.The direction of induced e.m.f can be found by

  • ALaplace?s law
  • BLenz?s law
  • CFleming?s right-hand rule
  • DKirchhoff?s voltage law
Answer / Hint Save Question Comment On Question
Correct Answer : (B)

Lenz?s law

Explanation:

The direction of induced e.m.f can be found by Lenz?s law.

11.Air-core coils are practically free from

  • A hysteresis losses
  • BEddy current losses
  • CBoth (a) and (b)
  • DNone of the above
Answer / Hint Save Question Comment On Question
Correct Answer : (C)

Both (a) and (b)

Explanation:

Air-core coils are practically free from  hysteresis losses and Eddy current losses.

12.The magnitude of the induced EMF in a conductor depends on the

  • AFlux density of the magnetic field
  • BRate of change of flux-linkages
  • CAmount of flux cut
  • DAmount of flux linkages
Answer / Hint Save Question Comment On Question
Correct Answer : (B)

Rate of change of flux-linkages

Explanation:

The magnitude of the induced EMF in a conductor depends on the Rate of change of flux-linkages.

13.Mutually inductance between two magnetically-coupled coils depends upon

  • APermeability of the core
  • BThe number of their turns
  • CCross-sectional area of their common core
  • DAll of the above
Answer / Hint Save Question Comment On Question
Correct Answer : (D)

All of the above

Explanation:

Mutually inductance between two magnetically-coupled coils depends upon Permeability of the core, The number of their turns and Cross-sectional area of their common core.

14.A laminated iron core has reduced eddy-current losses because

  • AMore wire can be used with less D.C resistance in coil
  • BThe laminations are insulated from each other
  • CThe magnetic flux is concentrated in the air gap of the core
  • DThe laminations are stacked vertically
Answer / Hint Save Question Comment On Question
Correct Answer : (B)

The laminations are insulated from each other

Explanation:

A laminated iron core has reduced eddy-current losses because The laminations are insulated from each other.

15.The law that the induced e.m.f and current always oppose the cause which produced it, is discovered by

  • AFaraday?s
  • BLenz
  • CNewton
  • DCoulomb
Answer / Hint Save Question Comment On Question
Correct Answer : (B)

Lenz

Explanation:

The law that the induced e.m.f and current always oppose the cause which produced it, is discovered by Lenz.

16.Which of the following is not a unit of inductance?

  • AHennery
  • BCoulomb/volt ampere
  • CVolt second/ampere
  • DAll of the above
Answer / Hint Save Question Comment On Question
Correct Answer : (B)

Coulomb/volt ampere

Explanation:

Coulomb/volt ampere is not a unit of inductance.

17.In case of an inductance, current is proportional to

  • AVoltage across the inductance
  • BMagnetic field
  • CNeither (a) nor (b)
  • DBoth (a) and (b)
Answer / Hint Save Question Comment On Question
Correct Answer : (B)

Magnetic field

Explanation:

In case of an inductance, current is proportional to Magnetic field.

18.For a purely inductive circuit which of the following ids true?

  • AApparent power is zero
  • BRelative power is zero
  • CActual power of the circuit is zero
  • DAny capacitance even if present in the circuit will not be charged
Answer / Hint Save Question
Correct Answer : (C)

Actual power of the circuit is zero

Explanation:

19.The unit of inductance is

  • AOhm
  • BHenry
  • CAmpere turns
  • DWeber/meters
Answer / Hint Save Question Comment On Question
Correct Answer : (B)

Henry

Explanation:

The unit of inductance is Henry.

20.An e.m.f of 16 volts is induced in a coil of inductance 4H. the rate of change of current must be

  • A64A/s
  • B32 A/s
  • C16 A/s
  • D4 a/s
Answer / Hint Save Question
Correct Answer : (D)

4 a/s

Explanation: