Free Printable Ch6- Electromagnetic Induction

Worksheets

Ch6- Electromagnetic Induction

Total questions: 50

Worksheet time: 28mins

Name

Class

Date

___ Law says that a current produced by an induced emf moves in a direction so that its magnetic field opposes the original change in flux

Lenz'

Faraday's

Ampere's

What would happen if I move a bar magnet in and out of a coil of copper wire?

Electric current would disappear

The magnet would explode

Electric current will flow through the wire

It would produce a gravitational field

Which action will increase the deflection of the galvanometer pointer?

The magnetic pole is reversed

The number of turns of coils is increased

The coil is made from insulated wire

The magnet is slowly pushed into the coil

As the north pole of the magnet is moved into the coil, the magnetic flux is _________.

increasing

decreasing

remains constant

depends on the speed of the magnet

What is the Pole at X

North

South

Voltage can be induced in a wire by

a. moving the wire near a magnet.

b. moving a magnet near the wire.

c. changing the current in a nearby wire.

d. all of these

The unit of magnetic flux is the

Henry

Tesla

Faraday

Weber

How would flipping the magnet in this experiment change the current?

The current would not change

The current would go to the right

There would be no current

The current would go CRAZY

A permanent magnet is quickly introduced into the center of an aluminum closed ring. With this ring ...

will be attracted to the magnet;

push away from the magnet;

remain stationary;

it will start to rotate about an axis passing through its center.

10.

The aircraft flies horizontally at a speed of 720 km / h. The wingspan of the aircraft is 20 m, the vertical component of the Earth's magnetic field is 50 µT. What is the difference in potential at the ends of the wings of the aircraft?

0.05 V

1 V

2 V

0.2 V

11.

The figure shows the scheme of the experiment. When the key is locked or opened, the galvanometer arrow is deflected. When will the relative position of the deflection coils be the maximum?

12.

When do we have self induction?

When the magnet moves into the coil

When the coil moves into the magnet

When a constant current passes through the coil

When a changing current passes through the coil

13.

Predict the direction of induced current in a metal ring when the ring is moved towards a straight conductor with constant speed v. The conductor is carrying current I in the direction shown in the figure.

(a)

14.

The electric current flowing in a wire in the direction from B to A is increasing. Find out the direction of the induced current in the metallic loop kept above the wire as shown.

(a)

15.

According to Lenz’s law the direction of an induced current in a conductor will be that which tends to produce which of the following effects?

enhance the effect which produces it

produce a greater heating effect

produce the greatest voltage

oppose the effect which produces it

16.

The north pole of a long bar magnet was pushed slowly into a short solenoid connected to a galvanometer. The magnet was held stationary for a few seconds with the north pole in the middle of the solenoid and then withdrawn rapidly. The maximum deflection of the galvanometer was observed when the magnet was

moving towards the solenoid

moving into the solenoid

at rest inside the solenoid

moving out of the solenoid

17.

There is a uniform magnetic field directed perpendicular and into the plane of the paper. An irregular shaped conducting loop is slowly changing into a circular loop in the plane of the paper. Then

current is induced in the loop in the anti-clockwise direction.

current is induced in the loop in the clockwise direction.

ac is induced in the loop.

no current is induced in the loop.

18.

Identify the wrong statement.

Eddy currents are produced in a steady magnetic field.

Eddy currents can be minimised by using laminated core

Induction furnace use eddy currents to produce heat

Eddy current can be used to produce braking force in moving trains.

19.

Which of the following does not use the application of eddy current?

Electric power meters

Induction furnace

LED lights

Magnetic brakes in trains

20.

Magnetic flux depends on

Magnetic Field

Area

Angle between Magnetic Field and Area Vector

All of the above

21.

The magnitude of the induced emf in a circuit is equal to the magnetic flux through the circuit

True

False

22.

In order to induce a voltage across a coil ____.

The coil must be in motion

Current must be increasing

There must be relative motion between the coil and the magnetic field

The coil must be cut by at least 10^8 lines of force per second

23.

The unit of inductance is:

volt

Ampere

Farad

Henry

24.

Lenz’s Law of electromagnetic induction is about the conservation of

Energy.

Mass.

Charges.

Momentum

25.

When the current in a coil is reduced uniformly

from 20 A to zero in 0.50 s, an e.m.f. of 4.0 V is induced in a neighbouring coil. What is the value of the mutual inductance between the two coils?

A 0.10 H

B 0.40 H

C 2.5 H

D 40 H

26.

Two coils X and Y arc arranged as shown in
the diagram below.

One quarter of the magnetic flux produced by the current in X is linked with Y. The mutual inductance between the coils is M. What is the mutual inductance when Y is the primary coil?

A $\frac{M}{4}$

B $\frac{M}{2}$

C $M$

D $4M$

27.

The correct expression for motional emf is

$Blv$

$NIBA$

$IlB$

$Blv^2$

28.

The production of a voltage across an inductor as a result of its own expanding or contracting magnetic field is called ____.

Flux density

Self-inductance

Counter emf

Faraday's second law

29.

A circular loop of flexible conducting material is kept in a magnetic field directed perpendicularly into its plane.

By holding the loop at diametrically opposite points its is suddenly stretched outwards, then

No current is induced in the loop

Anti-clockwise current is induced

Only e.m.f. is induced

Clockwise current is induced

30.

The magnetic flux through a coil varies with time t as shown in the diagram. Which graph best represents the variation of the e.m.f. E induced in the coil with time t?

31.

When a conducting wire XY is moved towards the right, a current flows in the anti-clockwise direction. Direction

of magnetic field at point O is

Along XY

Parallel to motion of wire

Perpendicular inside the paper

Perpendicular outside the paper

32.

A copper rod of length l is rotated about one end perpendicular to the uniform magnetic field B with constant
angular velocity $\omega$ . The induced e.m.f. between its two ends is

$Bl\omega^{2\ }$

$\frac{1}{2}Bl\omega\text{}^2$

$2Bl\omega^{2\ }\ ^{\ }$

$\frac{3}{2}Bl\omega^2$

33.

Eddy currents are induced when

A metal block is kept in a uniform magnetic field

Current is passed in a coil

A metal block is kept in a changing magnetic field

A coil is kept in a uniform magnetic field

34.

The current passing through a choke coil of self inductance 5 H is decreasing at the rate of 2 A/s. The e.m.f.

developed across the coil is

-5

-10

35.

A long solenoid has self inductance L. If its length is doubled keeping total number of turns constant then its

new self inductance will be

L/2

L/4

36.

In A.C generator,by increasing the no. of turns in the coil,

Decrease the Electromotive force (EMF)

Electromotive force (EMF) remains the same

Increases the Electromotive force (EMF)

Electromotive force (EMF) becomes zero

37.

AC generator converts:

Mechanical energy to electrical energy

Electrical energy to mechanical energy

Heat energy to mechanical energy

Chemical energy to electrical energy

38.

The direction of induced emf or current is indicated by:

Fleming’s left-hand rule

Fleming’s right-hand rule

Faraday’s law of electromagnetic induction

Ampere’s swimming rule

39.

In an a.c. generator, a coil with N turns, all of the same area A and total resistance R, rotates with frequency ω in a magnetic field B the maximum value of emf generated in the coil is:

NABR

NABω

NABRω

NAB

40.

What is true of AC GENERATOR?

It works on the principle of electromagnetic induction

The mechanical energy of the rotation is converted into electrical energy

A pair of slip rings are used in the AC generator

All the above

41.

What does the index finger show you in the Fleming’s right-hand rule?

Direction of current

Motion of wire

Direction of electric field

Direction of magnetic field

42.

The Fleming's right-hand rule is used when ....

motion causes current

current causes motion

current causes potential difference

motion causes magnetic field

43.

In the picture shown, what will be the direction of the current in wire MN?

Upward

Downward

Into the paper

Out of the paper

44.

In an AC generator, the contacts are made from a soft but highly conductive material, usually carbon, and are called....

Coils

Armatures

Slip Rings

Brushes

45.

Which of these is NOT a part of a DC Generator.

Slip rings

commutator

brushes

stator

46.

An inductor ____.

All of the above

Provides a specific value of inductance

Opposes any change in current

Stores energy in a magnetic field

47.

The production of a voltage across an inductor as a result of its own expanding or contracting magnetic field is called ____.

Flux density

Self-inductance

Counter emf

Faraday's second law

48.

1 Henry is equivalent to

Weber.Tesla

V.s/A

Tesla/s

Weber.A/s

49.

According to the Lenz’s Law,

the induced e.m.f is proportional to the magnetic field.

the direction of the induced e.m.f is such that it will oppose the change causing it.

Fleming’s Left hand rule can be used to determine the direction of induced e.m.f.

the induced e.m.f is always in opposite direction to the magnetic field.

50.