An iron rod of susceptibility \(599\) is subjected to a magnetising field of \(1200~\text{A m}^{-1}\). The permeability of the material of the rod is:\(\left(\mu_0 = 4 \pi\times 10^{-7}~\text{T m A}^{-1}\right)\)
1. \(8.0\times 10^{-5}~\text{T m A}^{-1}\)
2. \(2.4\pi\times 10^{-5}~\text{T m A}^{-1}\)
3. \(2.4\pi\times 10^{-7}~\text{T m A}^{-1}\)
4. \(2.4\pi\times 10^{-4}~\text{T m A}^{-1}\)
A bar magnet of magnetic moment \(1.5~\text{J/T}\) lies aligned with the direction of a uniform magnetic field of \(0.22~\text{T}\). What is the amount of work required by an external torque to turn the magnet so as to align its magnetic moment normal to the field direction?
1. \(0.66\) J
2. \(0.33\) J
3. \(0\)
4. \(0.44\) J
A circular coil of \(16\) turns and a radius of \(10~\text{cm}\) carrying a current of \(0.75~\text{A}\) rests with its plane normal to an external field of magnitude \(5.0\times 10^{-2}~\text{T}\). The coil is free to turn about an axis in its plane perpendicular to the field direction. When the coil is turned slightly and released, it oscillates about its stable equilibrium with a frequency of \(2.0~\text{s}^{-1}\)The moment of inertia of the coil about its axis of rotation is:
1. \(1.39\times 10^{-4}~ \text{kg m}^{2}\)
2. \(2.19\times 10^{-4} ~\text{kg m}^{2}\)
3. \(2.39\times 10^{-4} ~\text{kg m}^{2}\)
4. \(1.19\times 10^{-4}~\text{kg m}^{2}\)
A magnetic needle free to rotate in a vertical plane parallel to the magnetic meridian has its north tip pointing down at 22° with the horizontal. The horizontal component of the earth’s magnetic field at the place is known to be 0.35 G. The magnitude of the earth’s magnetic field at the place is:
1. 0.377 G
2. 0.278 G
3. 0.027 G
4. 0.101 G
A closely wound solenoid of 800 turns and area of cross-section carries a current of 3.0 A, is free to turn about the vertical direction and a uniform horizontal magnetic field of 0.25 T is applied, what is the magnitude of the torque on the solenoid when its axis makes an angle of with the direction of applied field?
1. \(7.5 \times 10^{-2}\ J\)
2. \(6.7 \times 10^{-3}\ J\)
3. \(7.5 \times 10^{-3}\ J\)
4. \(6.7 \times 10^{-2}\ J\)
A short bar magnet of magnetic moment is placed with its axis perpendicular to the earth’s field direction. At what distance from the center of the magnet, the resultant field is inclined at 45º with the earth’s field on its normal bisector.
(Magnitude of the earth’s field at the place is given to be 0.42 G. Ignore the length of the magnet in comparison to the distances involved.)
1. 5.6 cm
2. 6.3 cm
3. 5.0 cm
4. 6.5 cm
A short bar magnet placed in a horizontal plane has its axis aligned along the magnetic north-south direction. Null points are found on the axis of the magnet at 14 cm from the centre of the magnet. The earth’s magnetic field at the place is 0.36 G and the angle of dip is zero. What is the total magnetic field on the normal bisector of the magnet at the same distance as the null–point (i.e., 14 cm) from the centre of the magnet?
1. | 0.54 G in the direction of the earth's magnetic field. |
2. | 0.44 G in the opposite direction of the earth's magnetic field. |
3. | 0.54 G in the opposite direction of the earth's magnetic field. |
4. | 0.44 G in the direction of the earth's magnetic field. |
At a certain location in Africa, a compass points 12° west of the geographic north. The north tip of the magnetic needle of a dip circle placed in the plane of magnetic meridian points 60° above the horizontal. The horizontal component of the earth’s field is measured to be 0.16 G. The magnitude of the earth’s field at the location is:
1. 0.16 G
2. 0.48 G
3. 0.32 G
4. 0.30 G
A Rowland ring of mean radius \(15\) cm has \(3500\) turns of wire wound on a ferromagnetic core of relative permeability \(800.\) What is the magnetic field \(B\) in the core for a magnetizing current of \(1.2\) A?
1. \(3.27\) T
2. \(2.56\) T
3. \(1.05\) T
4. \(4.48\) T
A sample of paramagnetic salt contains atomic dipoles each of dipole moment The sample is placed under a homogeneous magnetic field of 0.64 T and cooled to a temperature of 4.2 K. The degree of magnetic saturation achieved is equal to 15%. What is the total dipole moment of the sample for a magnetic field of 0.98 T and a temperature of 2.8 K?
1. 9.219 J/T
2. 11.105 J/T
3. 10.336 J/T
4. 8.287 J/T