Q. No.Given below are two statements:
Assertion (A):
If a compass needle is kept at the magnetic north pole of the earth, the compass needle may stay in any direction.
Reason (R):
The dip needle will stay vertical at the north pole of the earth.
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.
Given below are two statements:
| Assertion (A): | The earth's magnetic field is due to iron present in its core. |
| Reason (R): | At a high-temperature magnet losses its magnetic property or magnetism. |
| 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. |
Given below are two statements:
| Assertion (A): | At most of the points in northern hemisphere, the magnetic field is inclined to an angle below horizontal, whereas in the southern hemisphere, the magnetic field is inclined to an angle above horizontal. |
| Reason (R): | The magnetic south pole is near the geographic north pole and vice versa. |
| 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. |
If \(\phi_1\) and \(\phi_2\) are the apparent angles of dip observed in two vertical planes at right angles to each other, then the true angle of dip \(\phi\) is given by:
1. \(cos^2{\phi}=cos^2{\phi_1}+cos^2{\phi_2}\)
2. \(sec^2{\phi}=sec^2{\phi_1}+sec^2{\phi_2}\)
3. \(tan^2{\phi}=tan^2{\phi_1}+tan^2{\phi_2}\)
4. \(cot^2{\phi}=cot^2{\phi_1}+cot^2{\phi_2}\)
A compass needle which is allowed to move in a horizontal plane is taken to a geomagnetic pole. It:
1. will become rigid showing no movement
2. will stay in any position
3. will stay in north-south direction only
4. will stay in east-west direction only
Electromagnets are made of soft iron because soft iron has:
1. low retentivity and high coercive force
2. high retentivity and high coercive force
3. low retentivity and low coercive force
4. high retentivity and low coercive force
1. Ferromagnetic material becomes paramagnetic material.
2. Paramagnetic material becomes diamagnetic material.
3. Paramagnetic material becomes ferromagnetic material.
4. Ferromagnetic material becomes diamagnetic material.
Above Curie temperature:
1. a ferromagnetic substance becomes paramagnetic.
2. a paramagnetic substance becomes diamagnetic.
3. a diamagnetic substance becomes paramagnetic.
4. a paramagnetic substance becomes ferromagnetic.
At point A on the earth's surface, the angle of dip is, . At a point B on the earth's surface, the angle of dip is, . We can interpret that:
| 1. | A and B are both located in the southern hemisphere. |
| 2. | A and B are both located in the northern hemisphere. |
| 3. | A is located in the southern hemisphere and B is located in the northern hemisphere. |
| 4. | A is located in the northern hemisphere and B is located in the southern hemisphere. |
The current of 30 A is flowing in a vertical straight wire. If the horizontal component of the earth's magnetic field is 2 x 10-5 Tesla, then the position of the null point will be:
1. 0.9 m
2. 0.3 mm
3. 0.3 cm
4. 0.3 m
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