A magnetic needle suspended parallel to a 

magnetic field requires $\sqrt{3}$ J of work to turn

it through $60°$. The torque needed to maintain 

the needle in this position will be

(1) $2\sqrt{3}$J                     

(2) 3 J

(3) $\sqrt{3}$ J                       

(4) $\frac{3}{2}$ J

There are four light-weight-rod samples; A, B, C, D separately suspended by threads. A bar magnet is slowly brought near each sample and the following observations are noted:

Which one of the following is true?

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 

1. zero

2. directed along OP

3. directed along PO

4. directed perpendicular to the plane of the paper

If a diamagnetic substance is brought near the north or the south pole of a bar magnet, it is:

A bar magnet having a magnetic moment of $2\times {10}^4 J{T}^{-1}$ is free to rotate in a horizontal plane. A horizontal magnetic field $B=6\times {10}^{-4}T$ exists in the space. The work done in taking the magnet slowly from a direction parallel to the field to a direction $60°$ from the field is 

(a) 0.6 J                            (b) 12 J

(c) 6 J                               (d) 2 J

Curie temperature is the temperature above which -

1. ferromagnetic material becomes paramagnetic material 

2. paramagnetic material becomes diamagnetic material 

3. paramagnetic material becomes ferromagnetic material 

4. ferromagnetic material becomes diamagnetic material  

Domain formation is the necessary feature of : 

(1) ferromagnetism                   (2) diamagnetism

(3) paramagnetism                   (4) all of these

The magnetic susceptibility of a paramagnetic substance at \(-73^\circ\text C\) is \(0.0060,\) then its value at \(-173^\circ \text C\) will be:
1. \(0.0030\)
2. \(0.0120\)
3. \(0.0180\)
4. \( 0.0045\)

The magnetic dipoles in a diamagnetic material are represented, for three situations. The three situations differ in magnitude if a magnetic field is applied to the material. In which situation the magnetization of the material is the greatest:
            

An iron rod of length L and magnetic moment M is bent in the form of a semicircle. Now its magnetic moment will be 

1. M

2. $\frac{2\mathrm{M}}{\mathrm{\pi }}$

3. $\frac{\mathrm{M}}{\mathrm{\pi }}$

4. $\mathrm{M\pi }$