In the figure, the magnetic needle has a magnetic moment of 6.7 × 10–2 Am2 and a moment of inertia I = 7.5 × 10–6 kg m2. It performs 10 complete oscillations in 6.70 s in a magnetic field. What is the magnitude of the magnetic field?
1. 0.02 T
2. 0.01 T
3. 003 T
4. 0.001 T
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?
A short bar magnet placed with its axis at \(30^{\circ}\) with an external field of \(800~\text{G}\) experiences a torque of \(0.016~\text{N-m}\). What is the work done in moving it from its most stable to the most unstable position?
1. \(0.036~\text{J}\)
2. \(0.016~\text{J}\)
3. \(0.064~\text{J}\)
4. \(0\)
A solenoid of cross-sectional area \(2\times 10^{-4}~\mathrm{m^2}\) and \(1000\) turns placed with its axis at \(30^\circ\) with an external field of \(800\) G experiences a torque of \(0.016\) Nm. The current flowing through the solenoid is:
1. \(2~\text{A}\)
2. \(4~\text{A}\)
3. \(1~\text{A}\)
4. \(5~\text{A}\)
The ratio of the magnitudes of the equatorial and axial fields due to a bar magnet of length \(5.0~\text{cm}\) at a distance of \(50~\text{cm}\) from its mid-point is:
(Given, the magnetic moment of the bar magnet is \(0.40~\text{Am}^{2}.\))
1. \(\frac{1}{2}\)
2. \(2\)
3. \(1\)
4. \(\frac{3}{2}\)
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:
1. | In configuration, the system is not in equilibrium. |
2. | In configuration, the system is unstable. |
3. | In configuration, the system is stable. |
4. | configuration corresponds to the lowest potential energy among all the configurations shown. |
Which of the following is the correct representation of magnetic field lines?
1. (g), (c)
2. (d), (f)
3. (a), (b)
4. (c), (e)
Which one of the following is correct?
1. | The magnetic field lines also represent the lines of force on a moving charged particle at every point. |
2. | Magnetic field lines can be entirely confined within the core of a toroid, but not within a straight solenoid. |
3. | A bar magnet exerts a torque on itself due to its own field. |
4. | Magnetic field arises due to stationary charges. |
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 \(2\) A. If the number of turns is \(1000\) per metre, the magnetic field intensity \(H\) is:
1. \(2\times10^2\) A/m
2. \(2\times10^3\) A/m
3. \(2\) A/m
4. \(20\) A/m
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:
1. \(10~\text{T}\)
2. \(1~\text{T}\)
3. \(0.1~\text{T}\)
4. \(2~\text{T}\)