 Home » Electrical Engineering » Electrical Engineering MCQ » Electromagnetic induction ### 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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

• BLenz
• CNewton
• DCoulomb

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

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)

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

Actual power of the circuit is zero

Explanation:

### 19.The unit of inductance is

• AOhm
• BHenry
• CAmpere turns
• DWeber/meters

Henry

Explanation:

The unit of inductance is Henry.

• A64A/s
• B32 A/s
• C16 A/s
• D4 a/s