When cooled below \(4.2\) K, mercury becomes a superconductor, which means it has no electrical resistance. When a current is passed through mercury under these conditions, which one of the following effects will be present?
(a) thermal
(b) chemical
(c) magnetic
1. | (a) and (c) only |
2. | (a), (b) and (c) |
3. | (b) only |
4. | (c) only |
Soft iron is used to manufacture electromagnets because:
1. It has a high permeability.
2. Its retentivity and coercivity are small.
3. Its retentivity and coercivity are high.
4. Both (1) & (2)
Assertion (A): | Magnetic flux linked with a closed surface is always zero. |
Reason (R): | Magnetic monopole does not exist. |
1. | Both (A) and (R) are true and (R) is the correct explanation of (A). |
2. | Both (A) and (R) are true but (R) is not the correct explanation of (A). |
3. | (A) is true but (R) is false. |
4. | (A) is false but (R) is true. |
i. | \(A\) is feebly repelled. |
ii. | \(B\) is feebly attracted. |
iii. | \(C\) is strongly attracted. |
iv. | \(D\) remains unaffected. |
1. | \(C\) is of a diamagnetic material. |
2. | \(D\) is of a ferromagnetic material. |
3. | \(A\) is of a non-magnetic material. |
4. | \(B\) is of a paramagnetic material. |
Which of the following is the correct representation of magnetic field lines?
1. (g), (c)
2. (d), (f)
3. (a), (b)
4. (c), (e)
1. | low hysteresis loss | 2. | high hysteresis loss |
3. | high permeability | 4. | both (1) and (3) |
1. | material \(A\) is preferred for making electromagnets. |
2. | material \(B\) is preferred for making permanent magnets. |
3. | material \(A\) is preferred for using electric generators and transformers. |
4. | all of these. |
Assertion (A): | Gauss's law for magnetism states that the net magnetic flux through any closed surface is zero. |
Reason (R): | The magnetic monopoles do not exist. North and South poles occur in pairs, allowing vanishing net magnetic flux through the surface. |
1. | (A) is true but (R) is false. |
2. | (A) is false but (R) is true. |
3. | Both (A) and (R) are true and (R) is the correct explanation of (A). |
4. | Both (A) and (R) are true but (R) is not the correct explanation of (A). |
Statement I: | The magnetic field of a circular loop at very far away point on the axial line varies with distance as like that of a magnetic dipole. |
Statement II: | The magnetic field due to magnetic dipole varies inversely with the square of the distance from the centre on the axial line. |
1. | Statement I is correct and Statement II is incorrect. |
2. | Statement I is incorrect and Statement II is correct. |
3. | Both Statement I and Statement II are correct. |
4. | Both Statement I and Statement II are incorrect. |