Q. No.The magnetic susceptibility is negative for:
1.
paramagnetic material only.
2.
ferromagnetic material only.
3.
paramagnetic and ferromagnetic materials.
4.
diamagnetic material only.
| 1. | paramagnetic material only. |
| 2. | ferromagnetic material only. |
| 3. | paramagnetic and ferromagnetic materials. |
| 4. | diamagnetic material only. |
A bar magnet of length \(l\) and magnetic dipole moment \(M\) is bent in the form of an arc as shown in the figure. The new magnetic dipole moment will be:
| 1. | \(\dfrac{3M}{\pi}\) | 2. | \(\dfrac{2M}{l\pi}\) |
| 3. | \(\dfrac{M}{ 2}\) | 4. | \(M\) |
| (i) | \(A\) is feebly repelled. | (ii) | \(B\) is feebly attracted. |
| (iii) | \(C\) is strongly attracted. | (iv) | \(D\) remains unaffected. |
Which one of the following is true?
| 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. |
A magnet is parallel to a uniform magnetic field. If it is rotated by \(60^{\circ}\), the work done is \(0.8\) J. How much work is done in moving it \(30^{\circ}\) further?
1. \(0.8\times 10^{7}~\text{ergs}\)
2. \(0.4~\text{J}\)
3. \(8~\text{J}\)
4. \(0.8~\text{ergs}\)
A closely wound solenoid of \(2000\) turns and area of cross-section \(1.5\times10^{-4}\) m2 carries a current of \(2.0\) A. It is suspended through its center and perpendicular to its length, allowing it to turn in a horizontal plane in a uniform magnetic field \(5\times 10^{-2}\) tesla making an angle of \(30^{\circ}\) with the axis of the solenoid. The torque on the solenoid will be:
1. \(3\times 10^{-3}\) Nm
2. \(1.5\times 10^{-3}\) Nm
3. \(1.5\times 10^{-2}\) Nm
4. \(3\times 10^{-2}\) Nm
A thin diamagnetic rod is placed vertically between the poles of an electromagnet. When the current in the electromagnet is switched on, then the diamagnetic rod is pushed up, out of the horizontal magnetic field. Hence the rod gains gravitational potential energy. The work required to do this comes from:
| 1. | the current source |
| 2. | the magnetic field |
| 3. | the lattice structure of the material of the rod |
| 4. | the induced electric field due to the changing magnetic field. |
A frog can be levitated in a magnetic field produced by a current in a vertical solenoid placed below the frog. This is possible because the body of the frog behaves as:
| 1. | Paramagnetic | 2. | Diamagnetic |
| 3. | Ferromagnetic | 4. | None of these |
| 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. |
Select the incorrect statement regarding magnetic material.
| 1. | The magnetic dipole moment of each atom of para and ferromagnetic substance is zero and that of diamagnetic material is non-zero in the absence of external magnetizing force |
| 2. | When the diamagnetic substance is brought near the north or south pole of a bar magnet, it is repelled |
| 3. | Magnetic susceptibility of diamagnetic substances is temperature independent and that of para and ferromagnetic substances is temperature-dependent |
| 4. | All of these |
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
Choose the correct option from the given ones:
| 1. | (a) and (c) only |
| 2. | (a), (b) and (c) |
| 3. | (b) only |
| 4. | (c) only |
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