A closely wound solenoid of 2000 turns and area of cross-section 1.5 × 10–4 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 × 10–2 tesla making an angle of 30° with the axis of the solenoid. The torque on the solenoid will be:
1. 3 × 10–3 Nm
2. 1.5 × 10–3 Nm
3. 1.5 × 10–2 Nm
4. 3 × 10–2 Nm
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 |
A vibration magnetometer placed in a magnetic meridian has a small bar magnet. The magnet executes oscillations with a time period of 2 s in the earth's horizontal magnetic field of 24 T. When a horizontal field of 18 T is produced opposite to the earth's field by placing a current-carrying wire, the new time period of the magnet will be:
1. 1 s
2. 2 s
3. 3 s
4. 4 s
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. | \(\frac{3M}{\pi}\) | 2. | \(\frac{2M}{l\pi}\) |
3. | \(\frac{M}{ 2}\) | 4. | \(M\) |
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. |
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 |
The material which is used to make permanent magnet has:
1. | High retentivity, low coercivity |
2. | Low retentivity, low coercivity |
3. | Low retentivity, high coercivity |
4. | High retentivity, high coercivity |
The magnetic moment of a magnet \((10 ~cm\times 4~cm\times1~cm)\) is \(4 ~Am^2\). Its intensity of magnetisation is:
1. 103 A/m
2. 102 A/m
3. 105 A/m
4. 104 A/m