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

If a magnet is suspended at an angle 30^o to the magnetic meridian, it makes an angle of 45^o with the horizontal. The real dip is

1. ${\tan }^{-1}\left(\frac{\sqrt{3}}{2}\right)$

2. ${\tan }^{-1}\left(\sqrt{3}\right)$

3. ${\tan }^{-1}\left(\sqrt{\frac{3}{2}}\right)$

4. ${\tan }^{-1}\left(\frac{2}{\sqrt{3}}\right)$

A cylindrical rod magnet has a length of 5 cm and a diameter of 1 cm. It has a uniform magnetization of 5.30 × 10³Amp/m³. What is its magnetic dipole moment?

1. $1\times {10}^{-2} J/T$                   

2. $2.08\times {10}^{-2} J/T$

3. $3.08\times {10}^{-2} J/T$              

4. $1.52\times {10}^{-2} J/T$

A dip needle lies initially in the magnetic meridian when it shows an angle of dip $\theta$ at a place. The dip circle is rotated through an angle x in the horizontal plane and then it shows an angle of dip $\theta \text{'}$. Then $\frac{\tan \theta \text{'}}{\tan \theta }$ is

1. 1/cos x

2. 1/sin x

3. 1/tan x

4. cos x

The variation of magnetic susceptibility $\left(\chi \right)$ with temperature for a diamagnetic substance is best represented by

1. 

2. 

3. 

4. 

The figure illustrates how B, the flux density, inside a sample of unmagnetized ferromagnetic material varies with B₀, the magnetic flux density, in which the sample is kept. For the sample to be suitable for making a permanent magnet:

1. OQ should be large and OR should be small

2. OQ and OR should both be large

3. OQ should be small and OR should be large

4. OQ and OR should both be small

A current-carrying loop is placed in a uniform magnetic field in four different orientations, I, II, III & IV. The decreasing order of potential energy is:

The magnetic susceptibility is negative for

1. paramagnetic material only

2. ferromagnetic material only

3. paramagnetic and ferromagnetic materials

4. diamagnetic material only