Two identical short bar magnets, each having magnetic moment M, are placed a distance of 2d apart with axes perpendicular to each other in a horizontal plane. The magnetic induction at a point midway between them is

 

(a)  $\frac{{\mu }_0}{4\mathrm{\pi }}\left(\sqrt{2}\right) \frac{M}{d^3}$                (b)  $\frac{{\mu }_0}{4\mathrm{\pi }}\left(\sqrt{3}\right) \frac{M}{d^3}$

(c)  $\left(\frac{2{\mu }_0}{4\mathrm{\pi }}\right)\frac{M}{d^3}$                 (d) $\frac{{\mu }_0}{4\mathrm{\pi }}\left(\sqrt{5}\right) \frac{M}{d^3}$

 

A superconductor exhibits perfect :
(1) Ferrimagnetism              

(2) Ferromagnetism

(3) Paramagnetism              

(4) Diamagnetism

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

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

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

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

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

The true value of angle of dip at a place is 60^o, the apparent dip in a plane inclined at an angle of 30^o with magnetic meridian is

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

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

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

(4)None of these

A vibration magnetometer consists of two identical bar magnets placed one over the other such that they are perpendicular and bisect each other. The time period of oscillation in a horizontal magnetic field is $2^{\raisebox{1ex}{$5$}\!\left/ \!\raisebox{-1ex}{$4$}\right.}$ seconds. One of the magnets is removed and if the other magnet oscillates in the same field, then the time period in seconds is:

1. $2^{\raisebox{1ex}{$1$}\!\left/ \!\raisebox{-1ex}{$4$}\right.}$
${\mathrm{2.\; 2}}^{\raisebox{1ex}{$1$}\!\left/ \!\raisebox{-1ex}{$2$}\right.}$
3. 2
4. $2^{\raisebox{1ex}{$3$}\!\left/ \!\raisebox{-1ex}{$4$}\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. $1.52\times {10}^{-2} J/T$

Two magnets of equal mass are joined at right angles to each other as shown the magnet 1 has a magnetic moment 3 times that of magnet 2. This arrangement is pivoted so that it is free to rotate in the horizontal plane. In equilibrium what angle will the magnet 1 subtend with the magnetic meridian

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

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

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

4. $0°$

Two magnets A and B are identical and these are arranged as shown in the figure. Their length is negligible in comparison to the separation between them. A magnetic needle is placed between the magnets at point P which gets deflected through an angle $\theta$ under the influence of magnets. The ratio of distance d₁ and d₂ will be:
   
1. $(2\tan \theta {)}^{1/3}$

2. $(2\tan \theta {)}^{-1/3}$

3. $(2cot\theta {)}^{1/3}$

4. $(2cot\theta {)}^{-1/3}$

Two short magnets of equal dipole moments M are fastened perpendicularly at their centres (figure). The magnitude of the magnetic field at a distance d from the centre on the bisector of the right angle is :

1. $\frac{{\mu }_0}{4\mathrm{\pi }} \frac{M}{d^3}$

2. $\frac{{\mu }_0}{4\mathrm{\pi }} \frac{M\sqrt{2}}{d^3}$

3. $\frac{{\mu }_0}{4\mathrm{\pi }} \frac{2\sqrt{2}M}{d^3}$

4. $\frac{{\mu }_0}{4\mathrm{\pi }} \frac{2M}{d^3}$