# CBSE Class 12 Physics Electromagnetic Induction MCQs

## MCQ for Class 12 Physics Electromagnetic Induction

Class 12 Physics students should refer to the following multiple-choice questions with answers for Electromagnetic Induction in standard 12. These MCQ questions with answers for Grade 12 Physics will come in exams and help you to score good marks

### Electromagnetic Induction MCQ Questions Class 12 Physics with Answers

Question: Whenever the magnetic flux linked with an electric circuit changes, an emf is induced in the circuit. This is called
(a) electromagnetic induction
(b) lenz’s law
(c) hysteresis loss
(d) kirchhoff’s laws

Question: According to Faraday’s law of electromagnetic induction
(a) electric field is produced by time varying magnetic flux.
(b) magnetic field is produced by time varying electric flux.
(c) magnetic field is associated with a moving charge.
(d) None of these

Question: Lenz’s law is a consequence of the law of conservation of
(a) charge
(b) mass
(c) energy
(d) momentum

Question: A magnet is moved towards a coil (i) quickly (ii) slowly, then the induced e.m.f. is
(a) larger in case (i)
(b) smaller in case (i)
(c) equal in both the cases
(d) llarger or smaller depending upon the radius of the coil

Question: A current carrying infinitely long wire is kept along the diameter of a circular wire loop, without touching it, the correct statement(s) is(are)
I. The emf induced in the loop is zero if the current is constant.
II. The emf induced in the loop is finite if the current is constant.
III. The emf induced in the loop is zero if the current decreases at a steady rate
(a) I only
(b) II only
(c) I and II
(d) I, II and III

Question: An induced e.m.f. is produced when a magnet is plunged into a coil. The strength of the induced e.m.f. is independent of
(a) the strength of the magnet
(b) number of turns of coil
(c) the resistivity of the wire of the coil
(d) speed with which the magnet is moved

Question: When current i passes through an inductor of self inductance L, energy stored in it is 1/2. L i2. This is stored in the
(a) current
(b) voltage
(c) magnetic field
(d) electric field

Question: A coil is wound on a frame of rectangular cross-section. If all the linear dimensions of the frame are increased by a factor 2 and the number of turns per unit length of the coil remains the same, self-inductance of the coil increases by a factor of
(a) 4
(b) 8
(c) 12
(d) 16

Question: The self inductance associated with a coil is independent of
(a) current
(b) time
(c) induced voltage
(d) resistance of coil

Question: The plane in which eddy currents are produced in a conductor is inclined to the plane of the magnetic field at an angle equal to

(a) 45°
(b) 0°
(c) 180°
(d) 90°

Question: Eddy currents are produced when
(a) A metal is kept in varying magnetic field
(b) A metal is kept in the steady magnetic field
(c) A circular coil is placed in a magnetic field
(d) Through a circular coil, current is passed

Question: Whenever the magnetic flux linked with an electric circuit changes, an emf is induced in the circuit. This is called
(a) electromagnetic induction
(b) lenz’s law
(c) hysteresis loss
(d) kirchhoff’s laws

Question: An induced e.m.f. is produced when a magnet is plunged into a coil. The strength of the induced e.m.f. is independent of
(a) the strength of the magnet
(b) number of turns of coil
(c) the resistivity of the wire of the coil
(d) speed with which the magnet is moved

Question: According to Faraday’s law of electromagnetic induction
(a) electric field is produced by time varying magnetic flux.
(b) magnetic field is produced by time varying electric flux.
(c) magnetic field is associated with a moving charge.
(d) None of these

Question: A moving conductor coil produces an induced e.m.f. This is in accordance with
(a) Lenz’s law
(c) Coulomb’s law
(d) Ampere’s law

Question: A coil of insulated wire is connected to a battery. If it is taken to galvanometer, its pointer is deflected, because
(a) the induced current is produced
(b) the coil acts like a magnet
(c) the number of turns in the coil of the galvanometer are changed
(d) None of these

Question: Lenz’s law is a consequence of the law of conservation of
(a) charge
(b) mass
(c) energy
(d) momentum

Question: A magnet is moved towards a coil (i) quickly (ii) slowly, then the induced e.m.f. is
(a) larger in case (i)
(b) smaller in case (i)
(c) equal to both the cases
(d) larger or smaller depending upon the radius of the coil

Question: The laws of electromagnetic induction have been used in the construction of a
(a) galvanometer
(b) voltmeter
(c) electric motor
(d) generator

Question: Two identical coaxial circular loops carry a current i each circulating in the same direction. If the loops approach each other, you will observe that the current in
(a) each increases
(b) each decreases
(c) each remains the same
(d) one increases whereas that in the other decreases

Question: If a coil made of conducting wires is rotated between poles pieces of the permanent magnet. The motion will generate a current and this device is called
(a) An electric motor
(b) An electric generator
(c) An electromagnet
(d) All of the above

Question: Magnetic flux is
(a) total charge per unit area.
(b) total current through a surface.
(c) total number of magnetic field lines passing normally through given area.
(d) total e.m.f. in closed circuit.

Question: In electromagnetic induction, the induced charge is independent of
(a) change of flux
(b) time.
(c) resistance of the coil
(d) None of these

Question: The induced e.m.f. in a rod of length l translating at a speed v making an angle θ with length l and perpendicular to magnetic field B is
(a) Blv
(b) Blv cos θ
(c) Blv sin θ
(d) Blv tan θ

Question: Len’z law provides a relation between
(a) current and magnetic field.
(b) induced e.m.f. and the magnetic flux.
(c) force on a conductor in magnetic field.
(d) current and induced e.m.f.

Question: A conducting loop is placed in a uniform magnetic field with its plane perpendicular to the field. An e.m.f. is induced in the loop, if
(a) it is translated.
(b) it is rotated about its axis.
(c) both (a) and (b).
(d) it is rotated about its diameter.

Question: Eddy currents do not produce
(a) heat
(b) a loss of energy
(c) spark
(d) damping of motion

Question: A coil of insulated wire is connected to a battery. If it is connected to galvanometer, its pointer is deflected, because
(a) induced current is set up
(b) no induced current is set up
(c) the coil behaves as a magnet
(d) the number of turns is changed

Question: A cylindrical bar magnet is kept along the axis of a circular coil. On rotating the magnet about its axis, the coil will have induced in it
(a) a current
(b) no current
(c) only an e.m.f.
(d) both an e.m.f. and a current

Question: Direction of current induced in a wire moving in a magnetic field is found using
(a) Fleming’s left found rule
(b) Fleming’s right hand rule
(c) Ampere’s rule
(d) Right hand clasp rule

Question: A circular coil expands radially in a region of magnetic field and no electromotive force is produced in the coil This is because
(a) the magnetic field is constant
(b) the magnetic field is in the same plane as the circular coil and it may or may not vary.
(c) the magnetic field has a perpendicular (to the plane of the coil) component whose magnitude is decreasing suitably.
(d) both (b) and (c)

Question: Whenever, current is changed in a coil, an induced e.m.f. is produced in the same coil. This property of the coil is due to
(a) mutual induction
(b) self induction
(c) eddy currents
(d) hysteresis

Question: When current i passes through an inductor of self inductance L, energy stored in it is 1/2. L i2. This is stored in the
(a) current
(b) voltage
(c) magnetic field
(d) electric field

Question: An inductor may store energy in
(a) its electric field
(b) its coils
(c) its magnetic field
(d) both in electric and magnetic fields

Question: Certain galvanometers have a fixed core made of nonmagnetic metallic material, when the coil oscillates, ...A... generated in the core ...B... the motion and bring the coil to rest ...C...
Here, A, B and C refer to
(a) induced emf, support, long time
(b) induced current, support, long time
(c) mechanical energy, oppose, long time
(d) eddy currents, oppose, quickly

Question: If in a galvanometer the coil is wound on a bad conductor, the eddy current will be
(a) zero
(b) maximum
(c) minimum
(d) 50% of the actual value

Question: The SI unit of inductance, the henry can be written as
(a) weber/ampere
(b) volt second/ampere
(c) joule/ampere2
(d) all of the above

Question: The mutual inductance between two coils depends on
(a) medium between the coils
(b) separation between the two coils
(c) orientation of the two coils
(d) All of the above

Question: When the plane of the armature of an a.c. generator is parallel to the field. in which it is rotating
(a) both the flux linked and induced emf in the coil are zero.
(b) the flux linked with it is zero, while induced emf is maximum.
(c) flux linked is maximum while induced emf is zero.
(d) both the flux and emf have their respective maximum values.

Question: The emf is induced in a single, isolated coil due to ...A...of flux through the coil by means of varying the current through the same coil. This phenomenon is called ...B...
Here, A and B refer to
(a) constancy, mutual induction
(b) change, self induction
(c) constancy, self induction
(d) changes, mutual induction

Question: Two coils, A and B, are lined such that emf ε is induced in B when the current in A is changing at the rate I. If current i is now made to flow in B, the flux linked with A will be
(a) (ε /I)i
(b) εi I
(c) (ε I)i
(d) i I/ε

Question: The polarity of induced emf is given by
(a) Ampere's circuital law
(b) Biot-Savart law
(c) Lenz’s law
(d) Fleming's right hand rule

Question: The self inductance of a coil is a measure of
(a) electrical inertia
(b) electrical friction
(c) induced e.m.f.
(d) induced current

Question: The coils in resistance boxes are made from doubled insulated wire to nullify the effect of
(a) heating
(b) magnetism
(c) pressure
(d) self induced e.m.f.

Question: Two pure inductors each of self inductance L are connected in series, the net inductance is
(a) L
(b) 2 L
(c) L/2
(d) L/4

Question: The self inductance associated with a coil is independent of
(a) current
(b) induced voltage
(c) time
(d) resistance of a coil

Question: A dynamo converts
(a) mechanical energy into thermal energy
(b) electrical energy into thermal energy
(c) thermal energy into electrical energy
(d) mechanical energy into electrical energy
(e) electrical energy into mechanical energy

Question: Choke coil works on the principle of
(a) transient current
(b) self-induction
(c) mutual induction
(d) wattless current

Question: Production of induced e.m.f. in a coil due to the changes of current in the same coil is
(a) self induction
(b) mutual induction
(c) dynamo
(d) none of these

Question: Henry is the S.I. unit of
(a) resistance
(b) capacity
(c) inductance
(d) current

Question: Mutual induction is the production of induced e.m.f. in a coil due to the changes of current in the
(a) same coil
(b) neighbouring coil
(c) both (a) and (b)
(d) neither (a) nor (b)

Question: The self inductance associated with a coil is independent of
(a) current
(b) time
(c) induced voltage
(d) resistance of coil

Question: Eddy currents are produced when
(a) A metal is kept in varying magnetic field
(b) A metal is kept in the steady magnetic field
(c) A circular coil is placed in a magnetic field
(d) Through a circular coil, current is passed

Question: Which of the following does not use the application of eddy current ?
(a) Electric power meters
(b) Induction furnace
(c) LED lights
(d) Magnetic brakes in trains

Question: Induction furnace make use of
(a) self induction
(b) mutual induction
(c) eddy current
(d) None of these

Question: When strength of eddy currents is reduced, as dissipation of electrical energy into heat depends on the ...A... of the strength of electrical energy into heat depends on the ...A... of the strength of electric current heat loss is
substantially ...B ... .
Here, A and B refer to
(a) cube, increase
(b) inverse, increased
(c) inverse, decreased
(d) square, reduced

Question: The plane in which eddy currents are produced in a conductor is inclined to the plane of the magnetic field at an angle equal to
(a) 45°
(b) 0°
(c) 180°
(d) 90°

Question: Which of the following is not the application of eddy currents?
(a) Induction furnace
(c) speedometer
(d) X-ray crystallography

Question: Eddy currents do not cause
(a) damping
(b) heating
(c) sparking
(d) loss of energy

Question: For magnetic breaking in trains, strong electromagnets are situated above the rails in some electrically powered trains. When the electromagnets are activated, the ...A... induced in the rails oppose the motion of the train. As
there are no ... B... linkages, the ...C... effects is smooth.
Here, A, B and C refer to
(a) eddy currents, mechanical, breaking
(b) induced currents, thermal, accelerating
(c) induced emf, mechanical, accelerating
(d) eddy currents, thermal, flying

Question: The pointer of a dead-beat galvanometer gives a steady deflection because
(a) eddy currents are produced in the conducting frame over which the coil is wound.
(b) its magnet is very strong.
(c) its pointer is very light.
(d) its frame is made of ebonite.

Question: When the plane of the armature of a generator is parallel to the field. in which it is rotating
(a) both the flux linked and induced emf in the coil are zero.
(b) the flux linked with it is zero, while induced emf is maximum.
(c) flux linked is maximum while induced emf is zero.
(d) both the flux and emf have their respective maximum values.

Question: When the current in a coil changes from 2 amp. to 4 amp. in 0.05 sec., an e.m.f. of 8 volt is induced in the coil. The coefficient of self inductance of the coil is
(a) 0.1 henry
(b) 0.2 henry
(c) 0.4 henr
(d) 0.8 henry

Question: Two coils of self inductances 2 mH and 8 mH are placed so close together that the effective flux in one coil is completely linked with the other. The mutual inductance between these coils is
(a) 6 mH
(b) 4 mH
(c) 16 mH
(d) 10 mH

Question: The mutual inductance of a pair of coils is 0.75 H. If current in the primary coil changes from 0.5 A to zero in 0.01 s, find average induced e.m.f. in secondary coil
(a) 25.5 V
(b) 12.5 V
(c) 22.5 V
(d) 37.5 V

Question: A wire of length 50 cm moves with a velocity of 300 m/min, perpendicular to a magnetic field. If the e.m.f. induced in the wire is 2 V, the magnitude of the field in tesla is
(a) 2
(b) 5
(c) 0.8
(d) 2.5

Question: The coefficient of self inductance of a solenoid is 0.18 mH. If a core of soft iron of relative permeability 900 is inserted, then the coefficient of self inductance will become nearly
(a) 5.4 mH
(b) 162 mH
(c) 0.006 mH
(d) 0.0002 mH

Question: Two solenoids of same cross-sectional area have their lengths and number of turns in ratio of 1 : 2 both. The ratio of self-inductance of two solenoids is
(a) 1 : 1
(b) 1 : 2
(c) 2 : 1
(d) 1 : 4

Question: A generator has an e.m.f. of 440 Volt and internal resistance of 4000 hm. Its terminals are connected to a load of 4000 ohm. The voltage across the load is
(a) 220 volt
(b) 440 volt
(c) 200 volt
(d) 400 volt

Question: The magnetic potential energy stored in a certain inductor is 25 mJ, when the current in the inductor is 60 mA. This inductor is of inductance
(a) 0.138 H
(b) 138.88 H
(c) 13.89 H
(d) None of these

Question: The two rails of a railway track, insulated from each other and the ground, are connected to millivoltmeter. What is the reading of the millivoltmeter when a train passes at a speed of 180 km/hr along the track, given that the vertical component of earth’s magnetic field is 0.2 × 10–4 wb/m2 and rails are separated by 1 metre
(a) 10–2 volt
(b) 10 mV
(c) 1 volt
(d) 1 mV

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