Two small bar magnets are placed in the air at a distance r apart. The magnetic force between them is proportional to:

1. $r^2$

2. $r^{-2}$

3. $r^{-3}$

4. $r^{-4}$

For an isotropic medium B,$\mathrm{\mu }$, H and M are related as (where B, ${\mathrm{\mu }}_0$, H and M have their usual meanings in the context of magnetic material )

1. $\left(\mathrm{B}-\mathrm{M}\right)={\mu }_{0}H$

2. $\mathrm{M}={\mathrm{\mu }}_0\left(\mathrm{H}+\mathrm{M}\right)$

3. $\mathrm{H}={\mathrm{\mu }}_0\left(\mathrm{H}+\mathrm{M}\right)$

4. $\mathrm{B}={\mathrm{\mu }}_0\left(\mathrm{H}+\mathrm{M}\right)$

Magnetic permeability is maximum for

1. Diamagnetic susbtance

2. Paramagnetic substance

3. Ferromagnetic substance

4. All of these

The magnetic field due to a short magnet at a point on its axis at a distance X cm from the middle point of the magnet is 200 Gauss. The magnetic field at a point on the neutral axis at a distance of X cm from the middle of the magnet is:

1. 100 Gauss

2. 400 Gauss

3. 50 Gauss

4. 200 Gauss

Two short magnets with their axes horizontally perpendicular to the magnetic meridian are placed with their centres 40 cm east and 50 cm west of the magnetic needle. If the needle remains undeflected, the ratio of their magnetic moments  is

1. 4:5

2. 16:25

3. 64:125

4. 2:$\sqrt{5}$

The magnetic field lines due to a bar magnet are correctly shown in

1.		2.
3.		4.	None of these

At a certain place, the horizontal component B₀ and the vertical component V₀ of the earth's magnetic field are equal in magnitude. The total intensity at the place will be

1. $B_0$                            2. $B_0^2$

3. $2B_0$                          4. $\sqrt{2}{B}_0$

A magnet is suspended in such a way that it oscillates in the horizontal plane. It makes 20 oscillations per minute at a place where dip angle is 30^o and 15 oscillations per minute at a place where dip angle is 60^o. The ratio of total earth's magnetic field at the two places is:

1. $3\sqrt{3}:8$
2. $16:9\sqrt{3}$
3. 4:9
4. $2\sqrt{3}:9$

If the angular momentum of an electron is $\overrightarrow{J}$ then the magnitude of the magnetic moment will be

1. $\frac{eJ}{m}$                           
2. $\frac{eJ}{2m}$
3. ej.2m                         
4. $\frac{2m}{eJ}$

Among the following properties describing diamagnetism identify  the property that is wrongly stated

1. Diamagnetic material do not have permanent magnetic moment

2. Diamagnetism is explained in terms of electromagnetic induction

3. Diamagnetic materials have a small positive susceptibility

4. The magnetic moment of individual electrons neutralize each other