Q. No.The following figures show the arrangement of bar magnets in different configurations. Each magnet has a magnetic dipole. Which configuration has the highest net magnetic dipole moment?
| 1. |  |
2. |  |
| 3. |  |
4. |  |
A bar magnet of length \(l\) and magnetic dipole moment \(M\) is bent in the form of an arc as shown in the figure. The new magnetic dipole moment will be:
| 1. | \(\dfrac{3M}{\pi}\) | 2. | \(\dfrac{2M}{l\pi}\) |
| 3. | \(\dfrac{M}{ 2}\) | 4. | \(M\) |
| 1. | \(\frac{MB}{F}\) | 2. | \(\frac{BF}{M}\) |
| 3. | \(\frac{MF}{B}\) | 4. | \(\frac{F}{MB}\) |
A magnetic needle suspended parallel to a magnetic field requires \(\sqrt{3}~\text{J}\) of work to turn it through \(60^\circ\)
1. \(3\) N-m
2. \(\sqrt{3} \) N-m
3. \(\frac32\) N-m
4. \(2\sqrt{3}\) N-m
| (i) | \(A\) is feebly repelled. | (ii) | \(B\) is feebly attracted. |
| (iii) | \(C\) is strongly attracted. | (iv) | \(D\) remains unaffected. |
Which one of the following is true?
| 1. | \(C\) is of a diamagnetic material. |
| 2. | \(D\) is of a ferromagnetic material. |
| 3. | \(A\) is of a non-magnetic material. |
| 4. | \(B\) is of a paramagnetic material. |
A short bar magnet of magnet moment \(0.4\) is placed in a uniform magnetic field of \(0.16\) . The magnet is in stable equilibrium when the potential energy is:
1. \(0.064\) J
2. \(-0.064\) J
3. zero
4.\(-0.082\) J
A vibration magnetometer placed in a magnetic meridian has a small bar magnet. The magnet executes oscillations with a time period of 2 s in the earth's horizontal magnetic field of 24 T. When a horizontal field of 18 T is produced opposite to the earth's field by placing a current-carrying wire, the new time period of the magnet will be:
1. 1 s
2. 2 s
3. 3 s
4. 4 s
The magnetic moment of a diamagnetic atom is:
1. 1
2. between zero and one
3. equal to zero
4. much greater than one
Two identical bar magnets are fixed with their centres at a distance \(d\) apart. A stationary charge \(Q\) is placed at \(P\) in between the gap of the two magnets at a distance \(D\) from the centre \(O\) as shown in the figure:
The force on the charge \(Q\) is in:
| 1. | direction along \(OP\) |
| 2. | direction along \(PQ\) |
| 3. | direction perpendicular to the plane of the paper |
| 4. | zero |
If a diamagnetic substance is brought near the north or the south pole of a bar magnet, it is:
| 1. | repelled by both the poles |
| 2. | repelled by the north pole and attracted by the south pole |
| 3. | attracted by the north pole and repelled by the south pole |
| 4. | attracted by both the poles |
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