$\mathrm{A} \mathrm{small} \mathrm{bar} \mathrm{magnet} \mathrm{is} \mathrm{placed} \mathrm{with} \mathrm{its} \mathrm{north} \mathrm{pole} \mathrm{facing} \mathrm{magnetic} \mathrm{north} \mathrm{pole}.$
$\mathrm{The} \mathrm{neutral} \mathrm{points} \mathrm{are} \mathrm{located} \mathrm{at} \mathrm{distance} \mathrm{r} \mathrm{from} \mathrm{its} \mathrm{centre}. \mathrm{If} \mathrm{magnet} \mathrm{is}$
$\mathrm{rotated} \mathrm{by} {180}^0, \mathrm{neutral} \mathrm{point} \mathrm{shall} \mathrm{be} \mathrm{obtained} \mathrm{at} \mathrm{distance}:$
$1. 2\mathrm{r} 2. \sqrt{2}\mathrm{r}$
$3. 2^{-\frac{1}{3}}\mathrm{r} 4. \frac{\mathrm{r}}{2\sqrt{2}}$

A neutral point is obtained at the centre of a vertical circular coil carrying current. The angle between the plane of the coil and the magnetic meridian is:

a) 0                           (b) 45°

(c) 60°                       (d) 90°

A magnet of magnetic moment M is situated with its axis along the direction of a magnetic field of strength B. The work done in rotating it by an angle of 180^o will be

(1) -MB                        

(2) +MB

(3) 0                            

(4) +2MB

A long magnetic needle of length 2L, magnetic moment M and pole strength m units is broken into two pieces at the middle. The magnetic moment and pole strength of each piece will be

1. $\frac{M}{2},\frac{m}{2}$

2. $M,\frac{m}{2}$

3. $\frac{M}{2},m$

4. M, m

Two identical thin bar magnets each of length l and pole strength m are placed at the right angle to each other with the north pole of one touching south pole of the other. The magnetic moment of the system is :

1. ml

2. 2ml

3. $\sqrt{2}ml$

4. $\frac{1}{2}ml$

Force between two identical bar magnets whose centres are r metre apart  is 4.8 N, when their axes are in the same line. If separation is increased to 2r, the force between them is reduced to

1. 2.4N                         2. 1.2N

3. 0.6N                         4. 0.3N

Two equal bar magnets are kept as shown in the figure. The direction of resultant magnetic field, indicated by arrow head at the point P is (approximately)

1. 

2. 

3. 

4. 

Two similar bar magnets P and Q, each of magnetic moment M, are taken. If P is cut along its axial line and Q is cut along its equatorial line, all the four pieces obtained have

1. Equal pole strength          2. Magnetic moment M/4

3. Magnetic moment M/2      4. Magnetic moment M

A dip needle in a plane perpendicular to magnetic meridian will remain:
1. Vertical
2. Horizontal
3. In any direction
4. At an angle of dip to the horizontal

The earth's magnetic field at a certain place has a horizontal component 0.3 Gauss and the total strength 0.5 Gauss. The angle of dip is:

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

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

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

4. ${\sin }^{-1}\left(\frac{3}{5}\right)$