The magnet of pole strength m and magnetic moment M, is cut into two pieces, along its axis. Its pole strength and magnetic moment now become
1.
2.
3.
4. m,M
If the areas under the I-H hysteresis loop and B-H hysteresis loop are denoted by , then
1.
2.
3.
4.
Two magnets A and B are identical and these are arranged as shown in the figure. Their lengths are negligible in comparision to the separation between them. A magnetic needle is placed between the magnets at point P and it gets delfected by an angle . The ratio of distances , will be
1.
2.
3.
4.
A bar magnet has pole strength 3.6 A-m and length 12 cm. Its area of cross section is 0.9 cm2. The magnetic field at the centre of the bar magnet is
1.
2.
3.
4.
The magnetic susceptibility of a paramagnetic substance at -73C is 0.0060, then its value at -173C will be
1. 0.0030
2. 0.0120
3. 0.0180
4. 0.0045
A deflection magnetometer is adjusted in the usual way. When a magnet is introduced, the deflection observed is , and the period of oscillation of the neddle in the magnetometer is T. When the magnet is removed, the period of oscillation is T0. The relation between T and T0 is
1.
2.
3.
4.
Two magnets are suspended by a given wire, one by one. In order to deflect the first magnet through 45, the wire has to be twisted through 540 whereas for the second magnet, the wire requires a twist of 360 for producing the same direction. Then, the ratio of magnetic moments of the two is
1. 11/7
2. 3/2
3. 4/3
4. 7/6
The plane of dip circle is set in the geographic meridian and the apparant dip is . It is then set in a vertical plane perpendicular to the geographic meridian. The apparent dip angle is . The declination at the place is
1.
2.
3.
4.
A bar magnet suspended by a suspension fibre, is placed in the magnetic meridian with no twist in the suspension fibre. On turning the upper end of the suspension fibre by an angle of 120 from the meridian, the magnet is deflected by an angle of 30 from the meridian. Then, the angle by which the upper end of the suspension fibre has to be twisted. so as to deflect the magnet through 90 from the meridian is
1. 270
2. 240
3. 330
4. 180
A magnetic dipole of magnetic moment M is rotated through 360 in a magnetic field B. The work done will be
1. MB
2. 2MB
3.
4. zero
A short magnet oscillated with a time period 0.1 s at a place where horizontal magnetic field is 24 . A downward current of 18 A is established in a vertical wire 20 cm east of the magnet. The new time period of oscillator
1. 0.1 s
2. 0.089 s
3. 0.076 s
4. 0.057 s
A short bar magnet placed with its axis at 30 with a uniform external magnetic field of 0.16 T, experiences a torque of magnitude 0.032 J. The magnetic moment of the bar magnet will be
1. 0.23
2. 0.40
3. 0.80
4. zero
M and are the magnetic dipole moments of the two magnets, which are joined to from a cross figure. The inclination of the system with the field, if their combination is suspended freely in a uniform external magnetic field B is
1.
2.
3.
4.
The value of is
1. >0
2. <0
3.
4. =0
Two bar magnets of the same mass, same length and breadth but having magnetic moments M and 2M, respectively are joined together pole to pole and suspended by a string. The time period of the assembly in a magnetic field of strength H is 3 seconds. If now the polarity of one of the magnetis is reversed and the combination is again made to oscillate in the same field, the time of oscillation is
1. 3 s
2. s
3. s
4. 6 s