A long solenoid has 1500 turns per metre and an iron core of = 1100 is kept inside it. 2A current flows in the coil of the solenoid. If the core is heated beyond curie temperature, then:
1. | The H and B fields in the solenoid reduce to zero. |
2. | The H and B fields in the solenoid remain unchanged. |
3. | The H field in the solenoid is nearly unchanged but B field decreases significantly. |
4. | The B field in the solenoid is nearly unchanged but the H field decreases significantly. |
The material suitable for making electromagnets should have:
1. High retentivity and high coercivity
2. High retentivity and low coercivity
3. Low retentivity and high coercivity
4. Low retentivity and low coercivity
Given below are two statements:
Assertion (A): | Magnetic dip at the pole is 0 ∘ . |
Reason (R): | Magnetic field at the pole is directed horizontally. |
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. | Both (A) and (R) are false. |
As we go from the magnetic equator towards the geographic south pole, the angle of the dip will become:
1. | More and more vertically downward and perpendicular to the surface at the magnetic pole. |
2. | More and more vertically upward and perpendicular to the surface at the magnetic pole. |
3. | Less and less vertically downward and horizontal at the magnetic pole. |
4. | Less and less vertically upward and horizontal at the magnetic pole. |
A material when heated suddenly changes its magnetic property at a particular temperature and above this temperature, its susceptibility is found to be inversely proportional to the absolute temperature. The material may be:
1. Ferromagnetic
2. Diamagnetic
3. Paramagnetic
4. Ferromagnetic or Paramagnetic
If a bar magnet is kept on a horizontal plane with N-pole of bar magnet facing geographic N-pole and S-pole of bar magnet facing geographic S-pole, then the number of neutral points is:
1. | 0 | 2. | 1 |
3. | 2 | 4. | Infinite |
A compass needle which is allowed to move in a horizontal plane is taken to a geomagnetic pole. It will:
1. stay in the east-west direction only.
2. stay in any position.
3. become rigid showing no movement.
4. stay in the north-south direction only.
At a place, the angle of dip is 30. If the horizontal component of the earth's magnetic field is B, the total intensity is:
1.
2.
3. 2B
4. B
The magnetic susceptibility χ of a ferromagnetic material varies with temperature, as:
1. | 2. | ||
3. | 4. |
Which of the following graphs represents the correct variation of the intensity of magnetisation (I) with the intensity of the magnetising field (H) in a ferromagnetic substance?
1. | 2. | ||
3. | 4. |