A short bar magnet placed with its axis at 30° with an external field of 800 G experiences a torque of 0.016 Nm. What is the magnetic moment of the magnet?

$$\begin{gathered} 1. 0.80 A m^2 \\ 2. 0.40 A m^2 \\ 3. 0.29 A m^2 \\ 4. 0.60 A m^2 \end{gathered}$$

A short bar magnet placed with its axis at 30° with an external field of 800 G experiences a torque of 0.016 N-m. What is the work done in moving it from its most stable to the most unstable position?

A solenoid of cross-sectional area $2\times {10}^{-4} m^2$ and 1000 turns placed with its axis at 30° with an external field of 800 G experiences a torque of 0.016 Nm. The current flowing through the solenoid is:

The ratio of the magnitudes of the equatorial and axial fields due to a bar magnet of length 5.0 cm at a distance of 50 cm from its mid-point is: (Given, the magnetic moment of the bar magnet is 0.40 A $m^2$)

$$\begin{gathered} 1. \frac{1}{2} \\ 2. 2 \\ 3. 1 \\ 4. \frac{3}{2} \end{gathered}$$

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:

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

Which one of the following is correct?

The earth’s magnetic field at the equator is approximately 0.4 G. The earth’s dipole moment is:

$$\begin{gathered} 1. 1.05\times {10}^{23} A m^2 \\ 2. 8.0\times {10}^{22} A m^2 \\ 3. 4.5\times {10}^{23} A m^2 \\ 4. 2.10\times {10}^{23} A m^2 \end{gathered}$$

In the magnetic meridian of a certain place, the horizontal component of the earth’s magnetic field is 0.26G and the dip angle is 60°. The magnetic field of the earth at this location 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 2A. If the number of turns is 1000 per metre, the magnetic field intensity H is:

$$\begin{gathered} 1. 2\times {10}^2 A/m \\ 2. 2\times {10}^3 A/m \\ 3. 2 A/m \\ 4. 20 A/m \end{gathered}$$

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 2A. 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 2A. If the number of turns is 1000 per metre, the magnetization, M is:

$$\begin{gathered} 1. 8\times {10}^5 A/m \\ 2. 6\times {10}^5 A/m \\ 3. 6.5\times {10}^5 A/m \\ 4 8.9\times {10}^5 A/m \end{gathered}$$

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 2A. If the number of turns is 1000 per metre, the magnetizing current $I_m \mathrm{is}:$

A domain in ferromagnetic iron is in the form of a cube of side length 1µm. The maximum possible dipole moment is:

[The molecular mass of iron is 55 g/mole and its density is 7.9 g/cm³. Assume that each iron atom has a dipole moment of 9.27×10^–24 A $m^2]$ 

^{$$\begin{gathered} 1. 8.0\times {10}^{-13} A m^2 \\ 2. 8.0\times {10}^{-12} A m^2 \\ 3. 7.0\times {10}^{-13} A m^2 \\ 4. 7.0\times {10}^{-12} A m^2 \end{gathered}$$}

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