# 12th Class Physics Mcqs Chapter no 15 | Physics Mcqs For Class 12th Mcqs 2021 with answers pdf

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Chapter 15

ELECTROMAGNETIC INDUCTION

1          The induced emf in a circuit depends upon choose which one is correct:

(a) Maximum magnetic flux

(b) Change in magnetic flux

(c) Initial magnetic flux

(d) Rate of charge of magnetic flux

2.         The induced current in a circuit depends upon choose which one is correct:

(a) Direction of the loop

(b) Shape of the loop

(c) Resistance of the loop

(d) Speed of the loop

3.         Which one of the following produced first choose which one is correct:

(a) Induced emf

(b) Induced current

(c) Motional emf

(d) None of the above

4.         The induced current can be increased by.

(a) Replacing the loop by a coil

(b) Moving the loop faster

(c) Using the strong magnetic field

(d) All of the above

5.         In a practical transformer, the output is always choose which one is correct:

(a) Equal to input

(b) Less than input

(c) Greater than input

(d) None of these

6.         If a closed metallic loop is moved across a magnetic field then choose which one is correct:

(a) Induced current is produced in it

(b) No induced current is produced

(c) Magnet will attract the loop

(d) None of above

7.         The Phenomenon by which an induced emf is produced in the conductor due to change of magnetic flux in it is called choose which one is correct:

(a) Electro magnetism

(b) Electromagnetic induction

(c) Electric polarization

(d) All of above

8.         The current produced by moving a loop (wire) across the magnetic field is called choose which one is correct:

(a) Alternating current

(b) Direct current

(c) Induced current

(d) None of these

9.         An ernf is set up in a conductor when it choose which one is correct:

(a) Moves across the magnetic field

(b) Is kept in the magnetic field

(c) Is kept in an electric field

(d) None of these

10.       The phenomenon of production of induced emf is called choose which one is correct:

(a) Magnetic induction

(b) Electromagnetic induction

(c) Both (a) and (b)

(d) None of these

11.       In magnet-coil experiment, emfcan be produced by choose which one is correct:

(a) Motion of loop and magnet

(b) Keeping the magnet stationary and moving the coil

(c) Keeping the coil stationary and moving magnet

(d) All of above

12.       Michael Faraday and Joseph Henry belongs to choose which one is correct:

(a) England and USA

(b) France and USA

(c) China and USA

(d) None of these

13.       A coil of constant area is placed in a constant magnetic field, an induced current is produced in the coil when choose which one is correct:

(a) The coil is rotated

(b) The coil is stationary

(c) Both (a) and (b)

(d) None of these

14.       The unit of induced emf is choose which one is correct:

(a) Ampere

(b) volt

(c) Joule/coulomb

(d) Both (b) and (c)

15.       When the conductor is moved with its length parallel to the lines of magnetic field choose which one is correct:

(a) emf passes through the conductor

(b) emf is induced across its ends

(c) Both (a) and (b)

(d) None of these

16.       The law of electromagnetic induction is related to choose which one is correct:

(a) Lenz

(c) Coulomb

(d) Ampere

17.       Faraday’s law of electromagnetic induction has been used in the construction of choose which one is correct:

(a) Electric generator

(b)  Ammeter

(c) Galvanometer

(d) All of above

18.       The Lenz’s law refers to choose which one is correct:

(a) Induced current

(b) Induced emf

(c) Both (a) & (b)

(d) None of these

19.       When we say that Lenz law refers to induced currents, it means that we can apply it directly to choose which one is correct:

(a) Open circuits

(b) Closed conducting loop

(c) Every circuits

(d) None of these

20.       The current produced due to electromagnetic induction is called choose which one is correct:

(a) Electric current

(b) Conventional current

(c) Induced current

(d) All of above

21.       The emf produced by the motion of a coil across the magnetic field is called choose which one is correct:

(a) Motional emf

(b) emf

(c) Induced emf

(d) None of the above

22.       The rate of change of magnetic flux is directly proportional to the induced emf is called choose which one is correct:

(a) Lenz law

(c) Oersted law

(d) None of them

23.       The main cause of power loss in transformer is choose which one is correct:

(a) Hysteresis

(b) Eddy current

(c) Both (a) and (b)

(d) None of these

24.       The direction of induced current is always so as to oppose the change which causes the current, this is the statement of choose which one is correct:

(a) Lenz’s law

(c) Ampere’s law

(d) Coulomb’s law

25.       Lenz’s law is also statement of choose which one is correct:

(a) Law of conservation of charge

(b) Law of conservation of energy

(c) Law of conservation of mass

(d) Law of conservation of momentum

26.       Faraday’s law was deduced in choose which one is correct:

(a) 1830

(b) 1841

(c) 1831

(d) 1931

27.       Lenz’s law presented in choose which one is correct:

(a) 1834

(b) 1934

(c) 1826

(d) 1836

28.       Lenz was a physicist.

(a) Japan

(b) China

(c) Russian

(d) None of above

29.       When we study the phenomenon mutual induction between two coils, the primary coil consists of choose which one is correct:

(a) A rheostat and battery

(b) A rheostat and galvanometer

(c) Galvanometer only

(d) None of these

30.       When we study mutual induction between two coils, the secondary coil circuit consists of choose which one is correct:

(a) A rheostat and battery

(b) A battery only

(c) A galvanometer only

(d) A rheostat only

31.       The emf induced in the secondary coil is directly proportional to choose which one is correct:

(a) Rate of change of magnetic flux

(b) Rate change of electric flux

(c) Change of magnetic flux

(d) All of above

32.       The negative sign in the equation shows that the induced emf in such a direction that it choose which one is correct: At

(a) Favours the current in the primary coil

(b) Opposes the current in the primary coil

(c) Opposes the change of current in the primary coil

(d) None of these

33.       The negative sign in the equation  can be explained by choose which one is correct:

(a) Lenz’s law

(c) Ampere’s law

(d) None of these

34.       If the current in the coil itself is increased by rheostat, the emf induced will be choose which one is correct:

(a) Opposite to that of battery

(b) In the same direction at that of battery

(c) Both (a) and (b)

(d) None of these

35.       Inductors behaves like the choose which one is correct:

(a) Resistors in D.C circuit

(b) Resistors in A.C circuit

(c) Both (a) and (b)

(d) None of these

36.       A coil of wire is also called choose which one is correct:

(a) Insulator

(b) Semi-conductor

(c) Inductor

(d) All of above

37.       The energy can be stored in the choose which one is correct:

(a) Magnetic field of an inductor

(b) Electric field of the capacitor

(c) Magnetic field of the capacitor

(d) Both (a) and (b)

38.       The symbol Um represents choose which one is correct:

(a) Energy density inside the coil

(b) Energy stored in a conductor

(c) Energy stored in an inductor

(d) All of above

39.       In order to minimize the power loss during transmission choose which one is correct:

(a) Resistance is reduced

(b) Current is increased

(c) Potential difference is increased

(d) Current is reduced

40.       Energy stored per unit volume inside a long solenoid is known as choose which one is correct:

(a) Energy density

(b) Power density

(c) Energy

(d) Surface charge density

41.       The phenomenon in which a change of current in one coil induces an emf in the other coil will be known as choose which one is correct:

(a) Self induction

(b) Mutual induction

(c) Electric induction

(d) None of above

42.       In an ideal case, the rate of change of flux in the secondary coil of transformer is choose which one is correct:

(a) Equal to that of primary

(b) Equal to that of secondary

(c) Greater than that of primary

(d) Smaller than that of primary

43.       The SI unit of mutual inductance is choose which one is correct:

(b) Coulomb

(c) Henry

(d) Ampere

44.       Which of the following is scalar choose which one is correct:

(a) Flux density

(b) emf

(c) Magnetic flux

(d) Both (a) and (b)

45.       The practical Illustration of the phenomenon of mutual induction in what among the following choose which one is correct:

(a) Transformer

(b) D.C. dynamo

(c) A.C. generator

(d) None of these

46.       One henry is equal to choose which one is correct:

(a) 1 ohm x 1 sec

(b) 1 ohm x 1 hertz

(c) 1 ohm x 1 metre

(d) All of above

47.       A magnetic compass will be deflected ifit is kept near a choose which one is correct:

(a) Charge at rest

(b) Charge in motion

(c) Positive charge at rest

(d) None of them

48.       The phenomenon of producing emf in a coil due to the change of current in itself is called choose which one is correct:

(a) Self induction

(b) Mutual induction

(c) Inductance

(d) Both (a) and (b)

49.       The SI unit of self inductance is choose which one is correct:

(a)        Ampere

(b) Coulomb

(d) Henry

50.       When current I passes through a resistance R, the power loss due to heating effect is choose which one is correct:

(a) Calculated by I2R

(b) Zero

(c) Maximum

(d) All of above

51.       The mutual induction between the two coils depends upon choose which one is correct:

(a) Area of the coil

(b) Number of turns

(c) Distance between the coil

(d) All Of the above

52.       The self induction does not depend upon choose which one is correct:

(a) Core material

(b) Weight of coil

(c) Number of turns of the coil

(d) Area of coil

53.       The coil from which the power is delivered to the circuit is called choose which one is correct:

(a) Primary coil

(b) Secondary coil

(c) Field coil

(d) None of these

54.       The coils of a transformer are choose which one is correct:

(c) Both (a) and (b)

(d) None of these

55.       The ratio of the self-induced emf to the rate of change of current in the coil will be called  choose which one is correct:

(a) Mutual induction

(b) Self induction

(c) Self inductance

(d) Mutual inductance

56.       The ratio of the emf in the secondary coil to the rate of change of current in the primary coil is known as choose which one is correct:

(a) Mutual induction

(b) Self induction

(c) Mutual inductance

(d) Both (a) and (c)

57.       If one coil is wound on an iron core, the flux through it will choose which one is correct:

(a) Remains constant

(b) Decrease

(c) Increase

(d) Becomes zero

58.       A 50 mH coil carries a current of 2A. The energy stored in its magnetic field is choose which one is correct:

(a) E = 005 J

(b) E= I0J

(c) E = 0.I J

(d) E = 50J

59.       A transformer has choose which one is correct:

(a) Two coil

(b) Only one coil

(c) Works on the principle of mutual induction

(d) None of these

60.       The windings of an electromagnet used in motors are called choose which one is correct:

(a) Armature coil

(b) Primary coil

(c) Secondary coil

(d) Field coils

61.       When a motor rotates, emf is induced. This induced emfis in such a direction that choose which one is correct:

(a) Helps the emf running the motor

(b) Opposes the emf running the motor

(c) Both (a) and (b)

(d) None of these

62.       A device that converts mechanical energy into electrical energy is called choose which one is correct:

(a) A.C generator

(b) Motor

(c) Converter

(d) Vibrator

63.       A transformer has no choose which one is correct:

(a) Hysteresis loss

(b) Copper loss

(c) Both (a) and (b)

(d) Mechanical loss

64.       A.C is converted into D.C by choose which one is correct:

(a) Dynamo

(b) Rectifier

(c) Motor

(d) Transformer

65.       An electric motor converts choose which one is correct:

(a) Mechanical energy into electrical energy

(b) Electrical energy into mechanical energy

(c) Magnetic energy into mechanical energy

(d) None of the above

66.       Emf produced by A.C generator depends upon choose which one is correct:

(a) Magnetic field strength

(b) Number of turns in the coil

(c) Frequency of rotation

(d) All the above

67.       Slip rings are used in choose which one is correct:

(a) Electric motor

(b) D.C Dynamo

(c) A.C generator

(d) None of above

68.       The product of induced current and resistance is always choose which one is correct:

(a) Lesser

(b) Greater

(c) Constant

(d) None of above

69.       Energy can be stored in a magnetic field of choose which one is correct:

(a) Inductor

(b) Resistance

(c) Solenoid

(d) Capacitor

70.       The principle of electric generator is based on choose which one is correct:

(b) Lenz law

(c) Ampere’s law

(d) None of above

71.       An electric motor consists of choose which one is correct:

(a) An armature

(b) A commutator

(c) Magnetic field

(d) All of above

72.       Alternating emf is produced by rotating a coil of wire in choose which one is correct:

(a) Electric field

(b) Magnetic field

(c) Conservative field

(d) Gravitational field

73.       An alternating current is that which choose which one is correct:

(a) Flows intermediately

(b) Varies in magnitude

(c) Reverses its direction several times per second

(d) None of the above

74.       An alternating current is converted into direct current by choose which one is correct:

(a) Dynamo

(b) Transformer

(c) Rectifier

(d) Motor

75.       The only difference between construction of D.C. generator and an A.C generator is that of choose which one is correct:

(a) Commutator

(b) Coil

(c) Carbon brushes

(d) Magnetic field

76.       A transformer is a device which choose which one is correct:

(a) Steps up D.C voltage

(b) Steps down D.C voltage

(c) Steps up or steps down A.C. voltage

(d) none

77.       A transformer consists of an iron core with choose which one is correct:

(a) A secondary coil

(b) A primary coil

(c) Neither primary nor secondary

(d) Primary coil and secondary coil

78.       A device consisting of two coils wound on iron core is called a choose which one is correct:

(a) Electric motor

(b) A.C generator

(c) Transformer

(d) D.C. generator

79.       The practical application of the phenomenon of mutual induction is choose which one is correct:

(a) A.C generator

(b) D.C generator

(c) Electric motor

(d) Transformer

80.       Who invented commutator choose which one is correct:

(a) William Black

(b) William Smith

(c) William Sturgeon

(d) Mosley

81.       Commutator was invented in choose which one is correct:

(a) 1834

(b) 1820

(c) 1840

(d) 1835

82.       Work can be stored in an inductor as choose which one is correct:

(a) Elastic P.E

(b) Electrical P.E

(c) Gravitational P.E

(d) Kinetic energy

83.       Energy stored per unit volume inside the solenoid is called choose which one is correct:

(a) Mass density

(b) Energy density

(c) Charge density

(d) Volume density

84.       A current which reverses its direction in each second is called choose which one is correct:

(a) Alternating current

(b) Direct current

(c) Induced current

(d) None of these

85.       Alternating current generator use choose which one is correct:

(a) Split rings

(b) Slip rings

(c) Loop rings

(d) Coiled rings

86.       The direction of the induced emf during electromagnetic induction can be determined by the use of choose which one is correct:

(a) Amperes law

(b) Coulomb’s law

(c) Lenz’s law            –

87.       A generator running in reverse direction may be called as choose which one is correct:

(a) D.C generator

(b) Commutator

(c) Motor

(d) A.C generator

88.       For the use of an electric lamp of low voltage on A.C main of high voltage, we use the device called

(a) Resistor

(b) Rheostat

(c) Transformer

(d) Solenoid

89.       Lenz’s law provides a relation between choose which one is correct:

(a) Current and magnetic field

(b) Force on a current carrying conductor and magnetic field

(c) Induced emf and the rate of change of magnetic flux

(d) None of these

90.       Lenz’s law does not violated the principle of choose which one is correct:

(a) Conservation of mass

(b) Conservation of energy

(c) Conservation of charge

(d) Conservation of momentum

91.       A straight line conductor of length 0.4 m is moved with speed of 7m/s perpendicular to the magnetic field 0.9 Wb/m . The induced emf across the conductor is choose which one is correct:

(a) 1.26 volt

(b) 25.2 volt

(c) 2.52 volt

(d) 5.04 volt

92.       The direction of the induced emf during electromagnetic induction is determined by choose which one is correct:

(a) Lenz’s law

(c) Ampere’s law

(d) None of these

93.       The knowledge of electromagnetic induction has been used in construction of choose which one is correct:

(a) Galvanometer

(b) Voltmeter

(c) Electric motor

(d) A.C generator

94.       If the north pole of a magnet moves away from a metallic ring. Then the current flows choose which one is correct:

(a) Clockwise

(b) Anticlockwise to

(c) First clockwise and then anticlockwise

(d) None of above

95.       If the number of turn in a coil is increased metallic ring to 3 times than its initial number, then the magnetic flux linked with is choose which one is correct:

(a) Becomes one third of its initial value

(b) Remains unchanged

(c) Becomes nine times of its initial value

(d) Increased by 3 times

96.       The movable wire is moved to the right causing an anticlockwise induced current. The direction of magnetic induction in the region P.

(a) Points to the right

(b) Points to the left

(c) Points up the paper

(d) Points down into the paper

97.       When the rate of change of current in a coil is unity then the induced emf will beequal to choose which one is correct:

(a) Number Of turns of the coil

(b) Total flux linked with the coil

(c) Coefficient of self inductance    (

d) None of the above

98.       When a current carrying conductor placed in an external magnetic field, experience a force. The device whose working based on this principle is choose which one is correct:

(a) Electric bell

(b) Electric motor

(c) Dynamo

(d) None of these

99.       If the load in the external circuit is greater, the current supplied by the generator is choose which one is correct:

(a) Very small

(b) Very large

(c) No change

(d) None of these

100.     A wire carrying the current placed in a magnetic field experience a force, this is the basic principle of choose which one is correct:

(a) Transformer

(b) D.C generator

(c) A.C generator

(d) Electric motor