1. | \(9~\text{gauss}\) | 2. | \(4~\text{gauss}\) |
3. | \(36~\text{gauss}\) | 4. | \(4.5~\text{gauss}\) |
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 \(800\) 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. \(5~\text{A}\)
1. | \(M\) | 2. | \(\dfrac{M\pi}{2}\) |
3. | \( \dfrac{M}{2\pi}\) | 4. | \(\dfrac{2M}{\pi}\) |
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. \(0\)
Four small identical bar magnets each of magnetic dipole moment \(M\) are placed on vertices of a square of side \(a\) such that diagonals of the square coincide with perpendicular bisectors of respective magnets. The net magnetic field at the centre of the square is:
1. | zero | 2. | \(\dfrac{\mu_{0}}{\sqrt{2 \pi}} \dfrac{M}{a^{3}}\) |
3. | \(\dfrac{2 \sqrt{2} \mu_{0}}{\pi} \cdot \dfrac{M}{a^{3}}\) | 4. | \(\dfrac{\mu_{0}}{\pi} \cdot \dfrac{M}{a^{3}}\) |