physics : class12 Coil and Magnet : Induced Current : Electromagnetic Induction and Alternating Currents MCQ Questions and Answers
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Coil and Magnet
MCQ questions and answers.
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MCQ Questions
1. What happens in a coil when a bar magnet is moved toward it?
A.
An induced current is produced in the coil
B.
The coil becomes permanently magnetized
C.
The coil stops conducting electricity forever
D.
The magnet loses all its magnetism immediately
Correct Answer:
An induced current is produced in the coil
Explanation:
Moving the magnet toward the coil changes the magnetic flux through the coil, producing an induced current.
2. A coil is connected to a galvanometer. What is observed when a magnet is pushed into the coil?
A.
The galvanometer shows a momentary deflection
B.
The galvanometer shows a constant deflection forever
C.
The galvanometer shows no deflection at any time
D.
The galvanometer is permanently damaged
Correct Answer:
The galvanometer shows a momentary deflection
Explanation:
The current is induced only while the magnetic flux through the coil is changing, so the galvanometer deflects momentarily.
3. What happens to the induced current when a magnet is held stationary inside a coil?
A.
It becomes maximum
B.
It becomes zero
C.
It continuously increases
D.
It reverses continuously
Correct Answer:
It becomes zero
Explanation:
When the magnet is stationary, the magnetic flux through the coil does not change, so no induced current flows.
4. If the north pole of a bar magnet is moved toward a coil, which pole is induced on the near face of the coil?
A.
North pole
B.
South pole
C.
Both north and south poles together
D.
No magnetic pole is induced
Correct Answer:
North pole
Explanation:
The near face of the coil becomes a north pole to oppose the approaching north pole of the magnet.
5. What is the effect of moving a magnet faster toward a coil?
A.
The induced current becomes larger
B.
The induced current becomes smaller
C.
The induced current becomes zero
D.
The coil loses its conducting property
Correct Answer:
The induced current becomes larger
Explanation:
Moving the magnet faster changes the magnetic flux more rapidly, resulting in a larger induced current.
6. A magnet is moved away from a coil. What happens to the direction of the induced current compared with when the magnet is moved toward the coil?
A.
It remains exactly the same
B.
It is reversed
C.
It becomes zero in every case
D.
It changes randomly
Correct Answer:
It is reversed
Explanation:
Reversing the motion of the magnet reverses the change in magnetic flux, so the induced current direction is reversed.
7. Which action can produce an induced current in a coil placed near a bar magnet?
A.
Moving the magnet relative to the coil
B.
Keeping both the magnet and coil stationary
C.
Replacing the coil with an insulator without movement
D.
Covering the magnet with paper while keeping it stationary
Correct Answer:
Moving the magnet relative to the coil
Explanation:
Relative motion between the magnet and coil changes the magnetic flux through the coil and induces current.
8. What is the direction of the induced current in a coil connected to a galvanometer when the south pole of a magnet is moved toward the coil?
A.
The direction is opposite to that produced by an approaching north pole
B.
The direction is exactly the same as for an approaching north pole
C.
No current can be induced by a south pole
D.
The current direction changes only after the magnet stops
Correct Answer:
The direction is opposite to that produced by an approaching north pole
Explanation:
The induced current always opposes the change in magnetic flux, so an approaching south pole produces a current opposite to that produced by an approaching north pole.
9. A coil is moved toward a stationary bar magnet. What is the result?
A.
An induced current is produced in the coil
B.
No current is produced because the magnet is stationary
C.
The coil becomes permanently charged
D.
The magnet immediately stops being magnetic
Correct Answer:
An induced current is produced in the coil
Explanation:
The coil and magnet have relative motion, so the magnetic flux through the coil changes and an induced current is produced.
10. When a bar magnet is pulled out of a coil, the induced current continues for how long?
A.
Only while the magnetic flux through the coil is changing
B.
For several hours after the magnet is removed
C.
Until the coil melts
D.
Forever, because the magnet was inside the coil
Correct Answer:
Only while the magnetic flux through the coil is changing
Explanation:
Induced current exists only during the change of magnetic flux, so it stops when the magnet and coil are no longer moving relative to each other.
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