A negative charge is given to a non-conducting loop and the loop is rotated in the plane of paper about its centre as shown in the figure. The magnetic field produced by the ring affects a small magnet placed above the ring in the same plane such that

       

1. the magnet does not rotate

2. the magnet rotates clockwise as seen from below

3. the magnet rotates anticlockwise as seen from below

4. no effect on the magnet is there

Figure shows a bar magnet and a long straight wire W, carrying current into the plane of paper. Point P is the point of intersection of axis of magnet and the line of shortest distance between magnet and the wire. If P is the mid-point of the magnet, then which of the following statements is correct?

1. magnet experiences a torque in the clockwise direction

2. magnet experiences a torque in anticlockwise direction

3. magnet experiences a force, normal to the line of shortest distance

4. magnet experiences a force along the line of shortest distance

In a permanent magnet at room temperature,

1. the magnetic moment of each molecule is zero.
2. the individual molecules have a non-zero magnetic moment which is all perfectly aligned.
3. domains are partially aligned.
4. domains are all perfectly aligned.

1. case (i) contradicts Gauss' law for electrostatic fields
2. case (ii) contradicts Gauss' law for magnetic fields
3. case (i) agrees with $\oint E.dl=0$
4. case (ii) contradicts $\oint H\cdot dI=I_{en}$

A paramagnetic sample shows a net magnetization of 8 ${\mathrm{Am}}^{-1}$ when placed in an external magnetic field of 0.6 T at a temperature of 4 K. When the same sample is placed in an external magnetic field of 0.2 T at a temperature of 16 K, the magnetization will be:

1. 32/3 ${\mathrm{Am}}^{-1}$
2. 2/3 ${\mathrm{Am}}^{-1}$
3. 6 ${\mathrm{Am}}^{-1}$
4. 2.4 ${\mathrm{Am}}^{-1}$

A long solenoid has 1000 turns per meter and carries a current of 1 A. It has a soft iron core of ${\mathrm{\mu }}_{\mathrm{r}}=1000$. The core is heated beyond the Curie temperature, ${\mathrm{T}}_{\mathrm{C}}.$

Essential difference between electrostatic shielding by a conducting shell and magnetostatic shielding is due to

(a) electrostatic field lines can end on charges and conductors have free charges
(b) lines of B can also end but conductors cannot end them
(c) lines of B cannot end on any material and perfect shielding is not possible
(d) shells of high permeability materials can be used to divert lines of B from the interior region

1. (a, b, c)

2. (a, c, d)

3. (b, c, d)

4. (c, d)

Let the magnetic field on the earth be modelled by that of a point magnetic dipole at the center of the earth. The angle of dip at a point on the geographical equator:

1. (a, b, c)
2. (a, c, d)
3. (b, c, d)
4. (c, d)