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
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
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
Nickel shows the ferromagnetic property at room temperature. If the temperature is increased beyond Curie temperature, then it will show:
3. no magnetic property
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.
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.
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
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: