Two bar magnets are held together tightly in a vibration magnetometer. When their like poles are together, they make 20 oscillations per minute and when their unlike poles are together, they make 8 oscillations per minute. The ratio of the magnetic dipole moments of two bar magnets is:

1. 29:21

2. 6:15

3. 1:6

4. 25:4

The magnetic susceptibility $\chi$ of a diamagnetic material depends on absolute temperature T as:

$1.$ $\chi$ $\propto$ $$ $T$ $$
$2.$ $\chi$ $\propto$ $\frac{1}{T}$
$3.$ $\chi$ $\propto$ $$ $T^0$ $$
$4.$ $\chi$ $\propto$ $\frac{1}{\sqrt{T}}$

The magnetic lines of force inside a bar magnet are:

The material which is used to make permanent magnet has:

Which of the following is not dimensionless?
(where symbols stand for their usual meanings in magnetism)

1. $\frac{I}{H}$

2. $\frac{B}{{\mu }_{0}H}$

3. ${\mu }_r$

4. $\frac{{\mu }_{r}B}{H}$

The magnetic moment of a magnet \((10 ~cm\times 4~cm\times1~cm)\) is \(4 ~Am^2\). Its intensity of magnetisation is:

1. 10³ A/m

2. 10² A/m

3. 10⁵ A/m

4. 10⁴ A/m

S.I. unit of intensity of magnetization is:

A ferromagnetic material is placed in an external magnetic field. The magnetic domains:

Due to a small magnet, the intensity at a distance \(x\) in the end-on position is \(9~\text{gauss}\). What will be the intensity at a distance \(\frac{x}{2}\) on equatorial position?
1. \(9~\text{gauss}\)
2. \(4~\text{gauss}\)
3. \(36~\text{gauss}\)
4. \(4.5~\text{gauss}\)

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

1. -2.45

2. 0.75

3. -0.5

4. 1.67