A closely wound solenoid of 2000 turns and area of cross-section as \(1.6\times10^{-4}\) m², carrying a current of 4.0 A, is suspended through its center allowing it to turn in a horizontal plane. The magnetic moment associated with the solenoid is:

1. 0.18 Am²
2. 3.24 Am²
3. 1.28 Am²
4. 0.38 Am²

Figure shows two small identical magnetic dipoles a and b of magnetic moments M each, placed at a separation 2d, with their axes perpendicular to each other. The magnetic field at the point P midway between the dipoles is:

1. $\frac{2{\mathrm{\mu }}_0\mathrm{M}}{4{\mathrm{\pi d}}^3}$

2. $\frac{{\mathrm{\mu }}_0\mathrm{M}}{4{\mathrm{\pi d}}^3}$

3. Zero

4. $\frac{\sqrt{5}{\mathrm{\mu }}_0\mathrm{M}}{4{\mathrm{\pi d}}^3}$

A magnetic needle suspended by a silk thread is vibrating in the earth's magnetic field. If the temperature of the needle is increased, then:

Choose the correct statement regarding magnetism.

A Gaussian surface is drawn enclosing the N-pole of a bar magnet. The net magnetic flux through the Gaussian surface will be:
(pole strength of N-pole is treated as positive and S-pole as negative)

The magnetization of a piece of iron or steel:

When a magnetic material is subjected to a very small magnetising force \(H,\) the intensity of magnetisation is proportional to:

The bar magnet \(A\) of magnetic moment \(M_A\) is found to oscillate at a frequency twice that of magnet \(B\) of magnetic moment \(M_B\) and the same moment of inertia when placed in a vibration magnetometer. We may say that:
1. \(M_B=8M_A\)
2. \(M_A= 4M_B\)
3. \(M_A=8M_B\)
4. \(M_A=2M_B\)

The possible value of magnetic susceptibility of a diamagnetic material can be:

1. -2.45

2. 0.75

3. -0.5

4. 1.67

The magnetic moment of a bar magnet of length \(L\) and area of cross-section \(A\) is \(M\). If the magnet is cut into four identical parts each of length \(L\) and area of cross-section \(\frac{A}{4}\), then magnetic moment of each part is: