NEET Physics Electromagnetic Induction MCQs

Question: A cylindrical bar magnet is rotated about its axis. A wire is connected from the axis and is made to touch the cylindrical surface through a contact. Then,
a) no current flows through the ammeter A
b) None of these
c) a direct current flows in the ammeter A
d) a time varying non-sinusoidal current flows through the ammeter A.
Answer: A

Question:  Assertion : Lenz's law violates the principle of conservation of energy.
Reason : Induced emf always opposes the change in magnetic flux responsible for its production
a) Assertion is correct, reason is correct; reason is a correct explanation for assertion
b) Assertion is correct, reason is correct; reason is not a correct explanation for assertion
c) Assertion is correct, reason is incorrect
d) Assertion is incorrect, reason is correct
Answer: A

Question: A long solenoid has 1000 turns. When a current of 4A flows through it, the magnetic flux linked with each turn of the solenoid is 4 × 10^–3 Wb. The self inductance of the solenoid is :
a) 1H
b) 2H
c) 3H
d) 4H
Answer: A

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) 2s
b) 1s
c) 3s
d) 4s
Answer: A

Question:  A coil is suspended in a uniform magnetic field, with the plane of the coil parallel to the magnetic lines of force. When a current is passed through the coil it starts oscillating; It is very difficult to stop. But if an aluminium plate is placed near to the coil, it stops. This is due to :
a) electromagnetic induction in the aluminium plate giving rise to electromagnetic damping
b) shielding of magnetic lines of force as aluminium is a paramagnetic material
c) induction of electrical charge on the plate
d) developement of air current when the plate is placed
Answer: A

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) 13.89 H
b) 138.88 H
c) Both
d) 1.389 H
Answer: A

Question: Assertion : In the phenomenon of mutual induction, self induction of each of the coil persists.
Reason : Self induction arises due to change in current in the coil itself. In mutual induction current changes in both the individual coil.
a) Assertion is correct, reason is correct; reason is a correct explanation for assertion
b) Assertion is correct, reason is correct; reason is not a correct explanation for assertion
c) Assertion is correct, reason is incorrect
d) Assertion is incorrect, reason is correct
Answer: A