physics : class12 Current Direction : Induced Current : Electromagnetic Induction and Alternating Currents MCQ Questions and Answers
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Current Direction
MCQ questions and answers.
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MCQ Questions
1. A north pole of a bar magnet is moved toward a conducting coil. As viewed from the magnet side, in which direction does the induced current flow in the coil?
A.
Clockwise
B.
Anticlockwise
C.
First clockwise and then anticlockwise
D.
No current flows
Correct Answer:
Anticlockwise
Explanation:
The approaching north pole increases magnetic flux through the coil. By Lenz's law, the near face of the coil becomes a north pole to oppose the approach, which requires anticlockwise current when viewed from the magnet side.
2. A north pole of a bar magnet is moved away from a conducting coil. As viewed from the magnet side, what is the direction of the induced current?
A.
Anticlockwise
B.
Clockwise
C.
No current flows
D.
It changes direction continuously
Correct Answer:
Clockwise
Explanation:
When the north pole moves away, the magnetic flux decreases. The coil produces a south pole on its near face to attract the magnet, requiring clockwise current as viewed from the magnet side.
3. When the south pole of a bar magnet is moved toward a coil, the face of the coil nearest the magnet becomes:
A.
A south pole
B.
A north pole
C.
Electrically neutral with no magnetic effect
D.
Alternately north and south
Correct Answer:
A south pole
Explanation:
The coil opposes the approach of the south pole according to Lenz's law. Therefore, its near face becomes south so that the two south poles repel each other.
4. A conducting loop is placed in a magnetic field directed into the page. If the magnetic field becomes stronger, the induced current in the loop is:
A.
Clockwise
B.
Anticlockwise
C.
Zero in every case
D.
Alternately clockwise and anticlockwise
Correct Answer:
Anticlockwise
Explanation:
The inward magnetic flux is increasing. The induced current must produce a magnetic field out of the page to oppose this increase. By the right-hand rule, an anticlockwise current produces an outward field.
5. A conducting loop is placed in a magnetic field directed out of the page. If the magnetic field becomes weaker, the induced current is:
A.
Clockwise
B.
Anticlockwise
C.
Always zero
D.
Unable to have a definite direction
Correct Answer:
Anticlockwise
Explanation:
The outward magnetic flux is decreasing. The induced current tries to maintain it by producing an outward magnetic field, which is produced by an anticlockwise current.
6. According to Lenz's law, the direction of induced current is such that it:
A.
Always supports the change in magnetic flux
B.
Opposes the change in magnetic flux
C.
Is always clockwise
D.
Is always anticlockwise
Correct Answer:
Opposes the change in magnetic flux
Explanation:
Lenz's law states that the induced current flows in a direction that opposes the change in magnetic flux responsible for producing it.
7. A magnet is held stationary inside a closed conducting coil. What is the direction of the induced current in the coil?
A.
Clockwise
B.
Anticlockwise
C.
It depends on the pole of the magnet
D.
No induced current flows
Correct Answer:
No induced current flows
Explanation:
A stationary magnet produces no change in magnetic flux through the stationary coil. Therefore, no induced emf or induced current is produced.
8. A loop is moved into a region where the magnetic field is directed into the page. The induced current produces a magnetic field:
A.
Into the page
B.
Out of the page
C.
Parallel to the plane of the loop
D.
With no definite direction
Correct Answer:
Out of the page
Explanation:
As the loop enters the field, inward magnetic flux increases. The induced field must oppose this increase, so it is directed out of the page.
9. When the north pole of a bar magnet is pushed into a coil, the near face of the coil acts as a north pole. This illustrates:
A.
Ohm's law
B.
Lenz's law
C.
Joule's law
D.
Coulomb's law
Correct Answer:
Lenz's law
Explanation:
The coil develops a north pole to oppose the approaching north pole of the magnet. This opposition of the change in magnetic flux is the basis of Lenz's law.
10. A loop is removed from a region of magnetic field directed out of the page. What is the direction of the magnetic field produced by the induced current?
A.
Out of the page
B.
Into the page
C.
Parallel to the plane of the loop
D.
The induced field is always zero
Correct Answer:
Out of the page
Explanation:
Removing the loop decreases the outward magnetic flux through it. The induced current produces an outward field to oppose this decrease, in accordance with Lenz's law.
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