Which of the following statements is incorrect?

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?

$1.<mspace\; width="1em"></mspace>0.80<mspace\; width="1em"></mspace>A<mspace\; width="1em"></mspace>m^2$
$2.<mspace\; width="1em"></mspace>0.40<mspace\; width="1em"></mspace>A<mspace\; width="1em"></mspace>m^2$
$3.<mspace\; width="1em"></mspace>0.29<mspace\; width="1em"></mspace>A<mspace\; width="1em"></mspace>m^2$
$4.<mspace\; width="1em"></mspace>0.60<mspace\; width="1em"></mspace>A<mspace\; width="1em"></mspace>m^2$

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 \(2\times 10^{-4}~\text{m}^2\) and \(1000\) turns placed with its axis at \(30^\circ\) with an external field of \(800~\text{G}\) experiences a torque of \(0.016~\text{Nm}.\) The current flowing through the solenoid is:
1. \(2~\text{A}\)
2. \(4~\text{A}\)
3. \(1~\text{A}\)
4. \(5~\text{A}\)