A bar magnet has coercivity \(4\times 10^{3}~\text{Am}^{-1}\). It is desired to demagnetize it by inserting it inside a solenoid \(12~\text{cm}\) long and having \(60\) turns. The current that should be sent through the solenoid is:
1. \(2\) A
2. \(4\) A
3. \(6\) A
4. \(8\) A
A uniform magnetic field, parallel to the plane of the paper existed in space initially directed from left to right. When a bar of soft iron is placed in the field parallel to it, the lines of force passing through it will be represented by:
1. | 2. | ||
3. | 4. |
A superconductor exhibits perfect:
1. Ferrimagnetism
2. Ferromagnetism
3. Paramagnetism
4. Diamagnetism
Two short magnets of equal dipole moments \(M\) are fastened perpendicularly at their centres (figure). The magnitude of the magnetic field at a distance \(d\) from the centre on the bisector of the right angle is:
1. | \(\frac{\mu_{0}}{4 \pi}\frac{M}{d^{3}}\) | 2. | \(\frac{\mu_{0}}{4 \pi}\frac{M \sqrt{2}}{d^{3}}\) |
3. | \(\frac{\mu_{0}}{4 \pi}\frac{2 \sqrt{2} M}{d^{3}}\) | 4. | \(\frac{\mu_{0}}{4 \pi}\frac{2 M}{d^{3}}\) |
The variation of magnetic susceptibility with temperature for a diamagnetic substance is best represented by:
1. | ![]() |
2. | ![]() |
3. | ![]() |
4. | ![]() |
The variation of the intensity of magnetisation \((I)\) with respect to the magnetising field \((H)\) in a diamagnetic substance is described by the graph:
1. | \(OD\) | 2. | \(OC\) |
3. | \(OB\) | 4. | \(OA\) |
There are four light-weight-rod samples; A, B, C, D separately suspended by threads. A bar magnet is slowly brought near each sample and the following observations are noted:
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 |
If a diamagnetic substance is brought near the north or the south pole of a bar magnet, it is:
1. | repelled by both the poles |
2. | repelled by the north pole and attracted by the south pole |
3. | attracted by the north pole and repelled by the south pole |
4. | attracted by both the poles |
The magnetic dipoles in a diamagnetic material are represented, for three situations. The three situations differ in magnitude if a magnetic field is applied to the material. In which situation the magnetization of the material is the greatest:
1. | \(A\) | 2. | \(B\) |
3. | \(C\) | 4. | Equal in \(A,B\) and \(C\) |
Two bar magnets are held together tightly in a vibration magnetometer. When their like poles are together, they make \(20\) oscillations per minute and when their unlike poles are together, they make \(8\) oscillations per minute. The ratio of the magnetic dipole moments of two bar magnets is:
1. \(29:21\)
2. \(6:15\)
3. \(1:6\)
4. \(25:4\)