Q. No.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
1. Ferromagnetic material becomes paramagnetic material.
2. Paramagnetic material becomes diamagnetic material.
3. Paramagnetic material becomes ferromagnetic material.
4. Ferromagnetic material becomes diamagnetic material.
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
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
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 current carrying coil is placed with its axis perpendicular to N-S direction. Let horizontal component of earth's magnetic field be and magnetic field inside the loop be H. If a magnet is suspended inside the loop, it makes angle with H. Then
1.
2.
3.
4.
The vertical component of the earth's magnetic field is zero at:
1. The magnetic poles.
2. The magnetic equator.
3. The geographic poles.
4. The geographic equator.
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. |
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