Figure shows the graph for magnetic hysteresis for a ferromagnetic materail. From the graph, magnetic retentivity for the material is-

 

1. 2.5 T

2. 1.2 T

3. 1 T

4. 4 T

A domain in ferromagnetic iron is in the form of a cube of side length \(1~\mu\text m.\) The maximum possible dipole moment is:
[The molecular mass of iron is \(55~\text{g/mole}\) and its density is \(7.9~\text{g/cm}^3.\) Assume that each iron atom has a dipole moment of \(9.27\times 10^{-24}~\text{Am}^2\)]
1. \(8.0\times10^{-13}~\text{Am}^2\)
2. \(8.0\times10^{-12}~\text{Am}^2\)
3. \(7.0\times10^{-13}~\text{Am}^2\)
4. \(7.0\times10^{-12}~\text{Am}^2\)

A solenoid has a core of material with relative permeability \(400\). The windings of the solenoid are insulated from the core and carry a current of \(2~\text{A}\). If the number of turns is \(1000\) per metre, the magnetization, \(M\) is:

A solenoid has a core of material with relative permeability \(400.\) The windings of the solenoid are insulated from the core and carry a current of \(2~\text{A}\). If the number of turns is \(1000\) per metre, the magnetising field \(B\) is:

A solenoid has a core of material with relative permeability \(400.\) The windings of the solenoid are insulated from the core and carry a current of \(2~\text A.\) If the number of turns is \(1000\) per metre, the magnetic field intensity \(H\) is:
1. \(2\times10^2~\text{A/m}\)
2. \(2\times10^3~\text{A/m}\)
3. \(2~\text{A/m}\) 
4. \(20~\text{A/m}\)

In the magnetic meridian of a certain place, the horizontal component of the earth’s magnetic field is \(0.26~\text{G}\) and the dip angle is \(60^{\circ}\). The magnetic field of the earth at this location is:
1. \(0.25~\text{G}\)
2. \(0.20~\text{G}\)
3. \(0.35~\text{G}\)
4. \(0.52~\text{G}\)

The earth’s magnetic field at the equator is approximately 0.4 G. The earth’s dipole moment is:
(Radius of earth, \(R_{E}=6.4\times10^{6} \) m)
1. \(1.05\times10^{23}\)$\mathrm{}$ A-m²
2. \(8.0\times10^{22}\) A-m²
3. \(4.5\times10^{23}\) A-m²
4. \(2.10\times10^{23}\) A-m²

Which one of the following is correct?

Which of the following is the correct representation of magnetic field lines?

The figure shows a small magnetized needle P placed at a point O. The arrow shows the direction of its magnetic moment. The other arrows show different positions (and orientations of the magnetic moment) of another identical magnetized needle Q. Then: