physics : class12 Moving Magnet : Induced Current : Electromagnetic Induction and Alternating Currents MCQ Questions and Answers
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Moving Magnet
MCQ questions and answers.
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MCQ Questions
1. A bar magnet is moved toward a coil connected to a galvanometer. What is observed?
A.
The galvanometer shows a momentary deflection
B.
The galvanometer shows a constant deflection
C.
The galvanometer shows no deflection
D.
The galvanometer needle breaks
Correct Answer:
The galvanometer shows a momentary deflection
Explanation:
Moving the magnet changes the magnetic flux through the coil, inducing a current for the duration of the motion. Therefore, the galvanometer gives a momentary deflection.
2. What happens when a bar magnet is held stationary inside a closed coil?
A.
A continuous current flows in the coil
B.
A momentary current flows continuously
C.
No induced current flows in the coil
D.
The coil becomes a permanent magnet immediately
Correct Answer:
No induced current flows in the coil
Explanation:
When the magnet is stationary, the magnetic flux through the coil does not change. Hence, no induced current is produced.
3. If the north pole of a bar magnet is moved toward a coil, the near face of the coil behaves like which pole?
A.
North pole
B.
South pole
C.
East pole
D.
It has no magnetic polarity
Correct Answer:
North pole
Explanation:
The near face of the coil becomes a north pole to oppose the approaching north pole of the magnet, according to Lenz's law.
4. If the north pole of a bar magnet is moved away from a coil, the near face of the coil behaves like which pole?
A.
North pole
B.
South pole
C.
Both north and south poles simultaneously
D.
It becomes electrically neutral permanently
Correct Answer:
South pole
Explanation:
When the north pole moves away, the coil produces a south pole on its near face to oppose the decrease in magnetic flux.
5. What is the effect on the induced current when a bar magnet is moved faster toward a coil?
A.
The induced current becomes larger
B.
The induced current becomes zero
C.
The induced current remains exactly unchanged
D.
The induced current changes into direct current
Correct Answer:
The induced current becomes larger
Explanation:
A faster-moving magnet changes the magnetic flux more rapidly, producing a larger induced emf and hence a larger induced current.
6. A bar magnet is moved into a coil and then withdrawn. What happens to the direction of induced current?
A.
It remains the same in both motions
B.
It reverses when the magnet is withdrawn
C.
It flows only during withdrawal
D.
It has no direction during either motion
Correct Answer:
It reverses when the magnet is withdrawn
Explanation:
The direction of the induced current depends on whether the magnetic flux is increasing or decreasing. Reversing the magnet's motion reverses the induced current.
7. A coil is connected to a galvanometer. A bar magnet is moved toward the coil, stopped, and then moved away. During which actions does the galvanometer deflect?
A.
Only while the magnet is stationary
B.
Only while the magnet is moving toward the coil
C.
While the magnet moves toward and away from the coil
D.
It never deflects
Correct Answer:
While the magnet moves toward and away from the coil
Explanation:
Induced current is produced whenever the magnet moves relative to the coil. No current is induced while the magnet is stopped, but current appears during both approach and withdrawal.
8. What is the main cause of induced current when a magnet is moved through a coil?
A.
Change in magnetic flux through the coil
B.
Heating of the magnet
C.
Increase in the mass of the coil
D.
Change in the color of the coil
Correct Answer:
Change in magnetic flux through the coil
Explanation:
The motion of the magnet changes the magnetic flux linked with the coil, which induces an emf and consequently a current in the closed coil.
9. A south pole of a bar magnet is moved toward a coil. What pole is produced on the near face of the coil?
A.
North pole
B.
South pole
C.
No pole under any condition
D.
An east pole
Correct Answer:
South pole
Explanation:
The coil develops a south pole on its near face to repel the approaching south pole of the magnet and oppose the change in magnetic flux.
10. A bar magnet is moved away from a coil, and the direction of its motion is then reversed. What happens to the induced current?
A.
Its direction reverses
B.
Its direction remains unchanged in all cases
C.
It permanently stops
D.
It becomes unrelated to the magnet's motion
Correct Answer:
Its direction reverses
Explanation:
Reversing the motion changes whether the magnetic flux through the coil is increasing or decreasing, so the direction of the induced current reverses.
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