MCQ On Class 12 Physics Chapter 6 Electromagnetic Induction

Questions
1 When the rate of change oic current is unity, the induced emf is equal to
A thickness of coil
B number of turns in coil
C coefficient of self inductance
D total flux linked with coil

Answer:coefficient of self inductance
2 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

Answer:LED lights

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3 The north pole of a bar magnet is rapidly introduced into a solenoid at one end (say A). Which of the following statements correctly depicts the phenomenon taking place?
A No induced emf is developed.
B The end A of the solenoid behaves like a south pole.
C The end A of the solenoid behaves like north pole.
D The end A of the solenoid acquires positive potential.

Answer:The end A of the solenoid behaves like north pole.
4 Which of the following statements is not correct?
A Whenever the amount of magnetic flux linked with a circuit changes, an emf is induced in circuit.
B The induced emf lasts so long as the change in magnetic flux continues.
C The direction of induced emf is given by Lenz’s law.
D Lenz’s law is a consequence of the law of conservation of momentum.

Answer:Lenz’s law is a consequence of the law of conservation of momentum.
5 Lenz’s law is a consequence of the law of conservation of
A charge
B energy
C induced emf
D induced current

Answer:energy
6 In the given figure current from A to B in the straight wire is decreasing. The direction of induced current in the loop is A

Class 12 Physics Chapter 6 Electromagnetic

A clockwise
B anticlockwise
C changing
D nothing can be said

Answer:anticlockwise
7 A solenoid is connected to a battery so that a steady current flows through it. If an iron core is inserted into the solenoid, the current will
A increase
B decrease
C remain same
D first increase then decrease

Answer:decrease
8 Two identical coaxial coils P and Q carrying equal amount of current in the same direction are brought nearer. The current in
A P increases while in Q decreases
B Q increases while in P decreases
C both P and Q increases
D both P and Q decreases

Answer:both P and Q decreases
9 The north pole of a long bar magnet was pushed slowly into a short solenoid connected to a short 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 The magnet was held stationary for a few seconds with the north pole in the middle of the solenoid and then withdrawn rapidly.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
A moving towards the solenoid
B moving into the solenoid
C at rest inside the solenoid
D moving out of the solenoid

Answer:moving out of the solenoid
10 A metal plate can be heated by
A passing either a direct or alternating current through the plate.
B placing in a time varying magnetic field.
C placing in a space varying magnetic field, but does not vary with time.
D both (a) and (b) are correct.

Answer:both (a) and (b) are correct.
11 If number of turns in primary and secondary coils is increased to two times each, the mutual inductance
A becomes 4 times
B becomes 2 times
C becomes A times
D remains unchanged 4

Answer:becomes 4 times
12 Two inductors of inductance .L each are connected in series with opposite? magnetic fluxes. The resultant inductance is (Ignore mutual inductance)
A zero
B L
C 2L
D 3L

Answer:2L
13 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
A current is induced in the loop in the anti-clockwise direction.
B current is induced in the loop in the clockwise direction.
C ac is induced in the loop.
D no current is induced in the loop.

Answer:current is induced in the loop in the anti-clockwise direction.
14 Faraday’s laws are consequence of the conservation of
A charge
B energy
C magnetic field
D both (b) and (c)

Answer:energy
15 Direction of current induced in a wire moving in a magnetic field is found using
A Fleming’s left hand rule
B Fleming’s right hand rule
C Ampere’s rule
D Right hand clasp rule

Answer:Fleming’s right hand rule
16 The energy stored in a 50 mH inductor carrying a current of 4 A is:
A 0.1 J
B 0.4 J
C 0.04 J
D 0.01 J

Answer:0.4 J
17 The magnetic flux linked with a coil is inversely proportional to the?
A magnetic field
B area of cross section
C number of turns
D none of these

Answer:magnetic field
18 The SI unit of magnetic flux is:
A T
B Tn-2
C Wb
D Wb m-2

Answer:Wb
19 coil of L = 8.4 mH and R = 6 Ω is connected to a 12 V battery. The current in the coil is 1.0 A at approx’time of:
A 500 s
B 20 s
C 35 ms
D 1 ms

Answer:1 ms
20 The role of inductance is equivalent to:
A inertia
B force
C energy
D momentum

Answer:inertia

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