# MCQs For NCERT Class 12 Physics Chapter 6 Electromagnetic Induction

Please refer to the MCQ Questions for Class 12 Physics Chapter 6 Electromagnetic Induction with Answers. The following Electromagnetic Induction Class 12 Physics MCQ Questions have been designed based on the latest syllabus and examination pattern for Class 12. Our experts have designed MCQ Questions for Class 12 Physics with Answers for all chapters in your NCERT Class 12 Physics book.

## Electromagnetic Induction Class 12 MCQ Questions with Answers

See below Electromagnetic Induction Class 12 Physics MCQ Questions, solve the questions and compare your answers with the solutions provided below.

Question. A long solenoid of diameter 0.1 m has 2 × 104 turns per meter. At the centre of the solenoid, a coil of 100 turns and radius 0.01 m is placed with its axis coinciding with the solenoid axis. The current in the solenoid reduces at a constant rate to 0 A from 4 A in 0.05 s. If the resistance of the coil is 10 p2 W, the total charge flowing through the coil during    this time is
(a) 16 mC
(b) 32 mC
(c) 16p mC
(d) 32p mC

B

Question. A coil of copper having 1000 turns is placed in a magnetic field (B = 4 × 10–5) perpendicular to its axis. The cross sectional area of the coil is 0.05 m2. If it turns through 180° in 0.01 second, then the e.m.f. induced in the coil will be ;
(a) 4 V
(b) 0.04 V
(c) 0.4 V
(d) 0.2 V

C

Question. For a coil having L = 2 mH, current flow through it is I = t2e–t then, the time at which emf becomes zero
(a) 2 sec
(b) 1 sec
(c) 4 sec
(d) 3 sec.

A

Question. In a coil of self inductance of 5 henry, the rate of change of current is 2 ampere per second, the e.m.f. induced in the coil is :
(a) 5 V
(b) – 5V
(c) – 10 V
(d) 10 V

C

Question. If the number of turns per unit length of a coil of solenoid is doubled, the self-inductance of the solenoid will
(a) remain unchanged
(b) be halved
(c) be doubled
(d) become four times

D

Question. According to Lenz’s law there is a conversion of:
(a) momentum
(b) collision
(c) voltage
(d) energy

D

Question. A 100 millihenry coil carries a current of 1A. Energy stored in its magnetic field is
(a) 0.5 J
(b) 1 J
(c) 0.05 J
(d) 0.1 J

C

Question. A 50 turn circular coil has a radius of 3 cm, it is kept in a magnetic field acting normal to the area of the coil. The magnetic field B is increased from 0.10 T to 0.35 T in 2 milli second, the average induced emf will be:
(a) 177 V
(b) 1.77 V
(c) 0.177 V
(d) 17.7 V

B

Question. In a region of magnetic induction B = 10–2 tesla, a circular coil of radius 30 cm and resistance p2 ohm is rotated about an axis which is perpendicular to the direction of B and which forms a diameter of the coil. If the coil rotates at 200 rpm the amplitude of the alternating current induced in the coil is
(a) 4π2 mA
(b) 30 mA
(c) 6 mA
(d) 200 mA

C

Question. A solenoid is 1.5 m long and its inner diameter is 4.0 cm. It has 3 layers of windings of 1000 turns each and carries a current of 2.0 amperes. The magnetic flux for a cross-section of the solenoid is nearly
(a) 4.1´10-5 weber
(b) 5.2´10-5 weber
(c) 6.31´10-3 weber
(d) 2.5´10-7 weber

C

Question. A conducting ring of radius 1 metre is placed in an uniform magnetic field B of 0.01 tesla oscillating with frequency 100 Hz with its plane at right angle to B. What will be the induced electric field ?
(a) pvolt /m
(b) 2volt /m
(c) 10 volt/m
(d) 62 volt/m

B

Question. Which of the following conclusion can be drawn from the result
ò B.dA = 0 ur ur Ñ
(a) magnetic field is zero everywhere
(b) magnetic monopole cannot exist
(c) magnetic lines of force do not intersect each other
(d) a current produces magnetic field

B

Question. A wheel with ten metallic spokes each 0.50m long is rotated with a speed of 120 rev/min in a plane normal to the earth’ s magnetic field at the place.
If the magnitude of the field is 0.40 G, the induced emf between the axle and the rim of the wheel is equal to
(a) 1.256 × 10 – 3 V
(b) 6.28 × 10 – 4 V
(c) 1.256 × 10 – 4 V
(d) 6.28 × 10 – 5 V

D

Question. A straight line conductor of length 0.4 m is moved with a speed of 7 m/s perpendicular to a magnetic field of intensity 0.9 Wb/m2. The induced e.m.f. across the conductor is
(a) 5.04 V
(b) 25.2 V
(c) 1.26 V
(d) 2.52 V

D

Question. The magnetic flux through a circuit carrying a current of 2.0 A is 0.8 weber. If the current reduces to 1.5 A in 0.1 s, the induced emf be :
(a) 2.0 V
(b) 4.0 V
(c) 8.0 V
(d) none of the above

A

Question. Fig represents an area A = 0.5 m2 situated in a uniform magnetic field B = 2.0 weber/m2 and making an angle of 60º with respect to magnetic field. The value of the magnetic flux through the area would be equal to
(a) 2.0 weber
(b) 3 weber
(c) 3 / 2 weber
(d) 0.5 weber

D

Question. Eddy currents are produced when
(a) a metal is kept in varying magnetic field
(b) a metal is kept in steady magnetic field
(c) a circular coil is placed in a magnetic field
(d) current is passed through a circular coil 6.9 Inductance

A

Question. A current of 2.5 A flows through a coil of inductance 5 H. The magnetic flux linked with the coil is
(a) 0.5 Wb
(b) 12.5 Wb
(c) zero
(d) 2 Wb

B

Question. A charged particle moves through a magnetic field in a direction perpendicular to it. Then the
(a) velocity remains unchanged
(b) speed of the particle remains unchanged
(c) direction of the particle remains unchanged
(d) acceleration remains unchanged

B

Question. The flux linked with a coil at any instant ‘t’ is given by f = 10t2 – 50t + 250. The induced emf at t = 3s is
(a) –190 V
(b) –10 V
(c) 10 V
(d) 190 V

B

Question. In an AC generator, a coil with N turns, all of the same area A and total resistance R, rotates with frequency w in a magnetic field B. The maximum value of emf generated in the coil is
(a) N.A.B.R.w
(b) N.A.B.
(c) N.A.B.R.
(d) N.A.B.w

D

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) 1.389 H
(d) 13.89 H

D

Question. In an inductor of self-inductance L = 2 mH, current changes with time according to relation i = t2e–t. At what time emf is zero?
(a) 4s
(b) 3s
(c) 2s
(d) 1s

C

Question. A circular disc of radius 0.2 meter is placed in a uniform magnetic field of induction 1π/(wb /m2) in such a way that its axis makes an angle of 60° with B. The magnetic flux linked with the disc is
(a) 0.08 Wb
(b) 0.01 Wb
(c) 0.02 Wb
(d) 0.06 Wb

C

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

C

Question. A wire loop is rotated in a magnetic field. The frequency of change of direction of the induced e.m.f. is
(a) four times per revolution
(b) six times per revolution
(c) once per revolution
(d) twice per revolution

D

Question. A 800 turn coil of effective area 0.05 mis kept perpendicular to a magnetic field 5 × 10–5 T. When the plane of the coil is rotated by 90° around any of its coplanar axis in 0.1 s, the emf induced in the coil will be
(a) 0.02 V
(b) 2 V
(c) 0.2 V
(d) 2 × 10–3 V

A

Question. A coil of resistance 400 W is placed in a magnetic field. If the magnetic flux f (Wb) linked with the coil varies with time t (sec) as f = 50t2 + 4. The current in the coil at t = 2 sec is
(a) 0.5 A
(b) 0.1 A
(c) 2 A
(d) 1 A

A

Question. A thin semicircular conducting ring (PQR) of radius r is falling with its plane vertical in a horizontal magnetic field B, as shown in the figure.
The potential difference developed across the ring when its speed is v, is
(a) zero
(b) Bvπr2 /2 and P is at higher potential
(c) prBv and R is at higher potential
(d) 2rBv and R is at higher potential

D

Question. A conducting circular loop is placed in a uniform magnetic field, B = 0.025 T with its plane perpendicular to the loop. The radius of the loop is made to shrink at a constant rate of 1 mm s–1. The induced emf when the radius is 2 cm, is
(a) 2p mV
(b) p mV
(c) π/2μ V
(d) 2 mV

B

Question. Two coils have a mutual inductance 0.005 H. The current changes in the first coil according to equation I = I0 sinwt, where I0 = 10 A and w = 100p rad/sec. The maximum value of e.m.f. in the second coil is
(a) p
(b) 5p
(c) 2p
(d) 4p

B

Question. A rectangular, a square, a circular and an elliptical loop, all in the (x – y) plane, are moving out of a uniform magnetic field with a constant velocity, V = v ^i . The magnetic field is directed along the negative z axis direction. The induced emf, during the passage of these loops, out of the field region, will not remain constant for
(a) the circular and the elliptical loops
(b) only the elliptical loop
(c) any of the four loops
(d) the rectangular, circular and elliptical loops

A

Question. What is the self-inductance of a coil which produces 5 V when the current changes from 3 ampere to 2 ampere in one millisecond?
(a) 5000 henry
(b) 5 milli-henry
(c) 50 henry
(d) 5 henry

B

Question. As a result of change in the magnetic flux linked to the closed loop as shown in the figure, an e.m.f. V volt is induced in the loop. The work done (joule) in taking a charge Q coulomb once along the loop is
(a) QV
(b) 2QV
(c) QV/2
(d) zero.

A

Question. A circular coil and a bar magnet placed nearby are made to move in the same direction. If the coil covers a distance of 1 m in 0.5. sec and the magnet a distance of 2 m in 1 sec, the induced e.m.f. produced in the coil is
(a) zero
(b) 0.5 V
(c) 1 V
(d) 2 V.

A

Question. A circular coil and a bar magnet placed nearby are made to move in the same direction. If the coil covers a distance of 1 m in 0.5. sec and the magnet a distance of 2 m in 1 sec, the induced e.m.f. produced in the coil is
(a) zero
(b) 0.5 V
(c) 1 V
(d) 2 V.

A

Question. A rectangular, a square, a circular and an elliptical loop, all in the (x – y) plane, are moving out of a uniform magnetic field with a constant velocity, V = v ^i . The magnetic field is directed along the negative z axis direction. The induced emf, during the passage of these loops, out of the field region, will not remain constant for
(a) the circular and the elliptical loops
(b) only the elliptical loop
(c) any of the four loops
(d) the rectangular, circular and elliptical loops

A

Question. The mutual inductance of a pair of coils, each of N turns, is M henry. If a current of I ampere in one of the coils is brought to zero in t second, the emf induced per turn in the other coil, in volt, will be
(a) MI/t
(b) NMI/t
(c) MN/It
(d) MI/Nt

A

Question. A rectangular coil of single turn, having area A, rotates in a uniform magnetic field B with an angular velocity w about an axis perpendicular to the field. If initially the plane of the coil is perpendicular to the field, then the average induced emf when it has rotated through 90° is

D

Question. A conducting circular loop is placed in a uniform magnetic field 0.04 T with its plane perpendicular to the magnetic field. The radius of the loop starts shrinking at 2 mm/s. The induced emf in the loop when the radius is 2 cm is
(a) 4.8p mV
(b) 0.8p mV
(c) 1.6p mV
(d) 3.4p mV

D

Question. If rotational velocity of a dynamo armature is doubled, then induced e.m.f. will become
(a) half
(b) two times
(c) four times
(d) unchanged

B

Question. A wire loop is rotated in a uniform magnetic field about an axis perpendicular to the field. The direction of the current induced in the loop reverses once each
(a) quarter revolution
(b) half revolution
(c) full revolution
(d) two revolutions

B

Question. In an AC generator, a coil with N turns, all of the same area A and total resistance R, rotates with frequency w in a magnetic field B. The maximum value of emf generated in the coil is
(a) N.A.B.R.w
(b) N.A.B.
(c) N.A.B.R.
(d) N.A.B.w

D

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

A

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

B

Question. A metal rod moves at a constant velocity in a direction perpendicular to its length. A constant uniform magnetic field exists in space in a direction perpendicular to the rod as well its velocity. Select correct statements (s) from the following.
(a) The entire rod is at the same potential
(b) There is an electric field in the rod
(c) The electric potential is highest at the centre
(d) The electric potential is lowest at its centre and increases towards its ends

B

Question. If the number of turns per unit length of a coil of solenoid is doubled, the self-inductance of the solenoid will
(a) remain unchanged
(b) be halved
(c) be doubled
(d) become four times

D

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

B

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