Question # 1

In a coil current change from 2 to 4 A in .05 s. If the average induced emf is 8V then coefficient of self-inductance is:

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0.2 henry

0.1 henry

0.8 henry

0.04 henry

An emf is set up in a conductor when it

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Is kept in a magnetic field

Is kept in an electric field

Moves across a magnetic field

Both A and B

None of these

A coil of constant area is placed in a constant magnetic field. An induced current is produced in the coil when:

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The coil is distorted

The coil is rotated

The coil is neither distorted nor rotated

Both A and B

None of these

Referring to above figure, current in coil P falls from its maximum value to zero

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At the instant the switch is closed

At the instant the switch is opened

When switch is kept open

When switch is kept closed

None of these

The rate change of area expressed is expressed in:

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m²s^-1

ms^-2

m²s^-2

ms^-1

None of these

A square loop of wire is moving through a uniform magnetic field. The normal to the loop is oriented parallel to the magnetic field. The emf induced in the loop is:

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Zero

Of smaller magnitude

Of larger magnitude

Sometimes B, sometimes C

Neither of these

The product of induced current and the resistance of the wire through which the current is passing is called:

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Electromagnetic induction

induced emf

Induced current

Self induced

None of these

Plan of a coil makes an angle of 20º with the lines of magnetic field. The angle between B and vector area of plane of coil is:

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Also 20º

70º

90º

180º

None of these

The induced current in the loop can be Increased by

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Using a stronger magnetic field

Moving the loop faster

Replacing the loop by a coil of many turns

All above

Both A and B

The phenomenon of generation of induced emf is called

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Electrostatic induction

Magnetic induction

Electromagnetic induction

Electric induction

Both (A) and (D)

When there is no relative motion between the magnet and coil, the galvanometer indicates:

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No current in circuit

An increasing current

A decreasing current

Either B or C

Which of the following is most suitable as the core of transformer

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Soft iron

Alinco

Steel

None of these

The induced current in a conductor depends upon:

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Resistance of the loop

Speed with which the conductor moves

Any of these

Both A and B

None of these

Motional emf is called motional:

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Electromagnetic force and is measured in newtons

Electromotive force and is measured in volt

Electromotive force and is measured in newtons

Electromagnetic force and is measured in volts

None of these

The motional e.m.f depends upon the

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Length of a conductor

Strength of a magnet

Speed of the conductor

All of the above

Faraday's law of electromagnetic induction has been used in the construction of:

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Galvanometer

Voltmeter

Electric motor

Electric genrator

Commutator

An induced current can be produced by:

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Constant magnetic field

Changing magnetic field

Varying magnetic field

Constant electric field

None of these

The current produced by moving a loop of wire across a magnetic field is called

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Direct current

Magnetic current

Alternating current

Induced current

None of these

Which of the following quantities remain constant in step up transformer?

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Current

Voltage

Power

Heat

The unit of induced emf is:

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Volt

Nm/As

Joule coul^-1

Both A and C

All of these

Referring to above figure, due to change in current in the coil P, the change in magnetic flux

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Is associated with coil P

Is associated with coil S

Causes and induced current in coil S

All of these

None of these

The magnitude of induced emf depends upon the:

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Rate of decrease of magnetic field

Rate of change of magnetic field

Rate of increase of magnetic flux

Constancy of magnetic field

None of these

The induced current is a conductor depends upon:

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Resistance of the loop

Speed with which the conductor moves

Any of these

Both (A) and (B)

None of these

Self inducede e.m.f. is also called

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Motional e.m.f.

Thermistor

Electrostatic induction

Back e.m.f

In magnet-coil experiment, emf can be produced by:

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Keeping the coil stationary and moving the magnet

Keeping the magnet stationary and moving the coil

Relative motion of the loop and magnet

Any one of above

All above

In the equilibrium state, the potential difference between two ends of the conductor moving across a magnetic field is called:

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Motion emf

Electrostatic emf

Induced emf

Both A and B

Both A and C

A coil of constant area is placed in a constant magnetic field. An induced current is produced in the coil when

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The coil is distorted

The coil is rotated

The coil is neither distorted nor rotated

Both A and B

None of these

The change of magnetic flux through a circuit will produce

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Magnetic Field

Electric Field

emf

a.c

The induced emf in a coil is proportional to:

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Magnetic flux through a coil

Rate of change of magnetic flux through the coil

Area of the coil

Product of magnetic flux and area of the coil

When a conductoris moved across a magnetic field:

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Emf induced its similar to that of a battery

Emf induced gives rise to induced current

An emf is induced across its ends

All are correct

None of these

Referring to above figure, current in the coil P grows from zero to its maximum value

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At the instant the switch is closed

At the instant the switch is opened

When switch is kept open

All of above

Neither of above

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ECAT Pre General Science Physics Chapter 15 Electromagnetic Induction Online Test MCQs With Answers

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