Question 3 :
A compass needle whose magnetic moment is $$60 A m^2$$ pointing geographical north at a certain place where the horizontal component of earth's magnetic field is $$40 \times 10^{-6} Wb m^{-2}$$ experiences a torque of $$1.2 \times 10^{-3} N m.$$ The declination of the place is<br><br>

Question 5 :
<span class="wysiwyg-font-size-medium"><span class="wysiwyg-font-size-medium"><p class="wysiwyg-text-align-left">The value of angle of dip is zero at the magnetic equator because on it :<br></p>

Question 7 :
Which of the following substances magnetic susceptibility$$\displaystyle { X }_{ m }$$ is negative?

Question 8 :
The magnetic moment produced in a substance of 1 g is $$6 \times 10^{-7}\, A-m^2$$. If its density is $$5 \,\,g/cm^3$$, then the intensity of magnetisation in A/m will be :<br/>

Question 9 :
State whether True or False :Hysteresis is the number of lines of force per unit area in a magnetic field.

Question 10 :
The magnetic moment of a bar magnet of length $$20\ cm$$ is $$3.6 \times 10^{-6} Am^{2}$$. The magnetic length is $$90\%$$ of its geometric length. The pole strength is:

Question 11 :
If a magnetic material is having magnetic susceptibility $$(\chi)=-1$$, then the relative magnetic permeability $$(\mu_r)$$ and type of magnetic material is?

Question 12 :
At a place on Earth, the vertical component of Earth's magnetic field is $$\sqrt { 3 } $$ times its horizontal component. The angle of dip at this place is ___________

Question 14 :
Point out the wrong statement about the magnetic properties of soft iron and steel

Question 17 :
Every iron atom in a ferromagnetic domain in iron has a magnetic dipole moment equal to $$9.27 \times 10^{-24} \ A-m^2$$. A ferromagnetic domain in iron has the shape of a cube of side $$1 \mu m$$. The maximum dipole moment occurs when all the dipoles are aligned. The molar mass of iron is $$55 \ g$$ and its specific gravity is $$7.9$$. The magnetisation of the domain is:

Question 18 :
A short magnet is arranged with its axis along east-west. A compass box is placed on its axial line at a distance of $$20\ cm$$ from centre. If the deflection is $$45$$. Find moment of magnet $$(B_{H} = 0.4\times 10^{-4}T)$$.

Question 19 :
A magnetizing field of 1600A/m producers a magnetic flux of 2 x $$10^{-5}$$ Wb in a bar of iron of cross section 0.2 x $$10^{-4}m^2$$. Calculate the susceptibility of the bar.

Question 20 :
A magnetic needle suspended by a silk thread is vibrating in the earth's magnetic field. If temperature of the needle is increased to $$1000^0C$$, then

Question 21 :
A planar coil of area 7 $$\mathrm{m}^{2}$$ carrying an anti-clockwisecurrent 2 A is placed in an extemal magnetic field $$\vec{B}=(0.2\hat{i}+0.2\hat{j}-0.3\hat{k})$$, such that the normal to the plane is along the line$$(3\hat{i}-5\hat{j}+4\hat{k})$$. Select correct statements from the following . ( Consider Normal of the coiland Magnetic moment vectors to be inthe same direction )<br>

Question 22 :
A coil of radius R carries a current I. Another concentric coil of radius $$\displaystyle r\left( r&lt;&lt;R \right)$$ caries current$$\displaystyle \frac { I }{ 2 }$$. Initially planes of the two coils are mutually perpendicular and both the coils are free to rotate about common diameter. They are released from rest from this position. The masses of the coils are M and m respectively$$\displaystyle \left( m&lt;M \right)$$. During the subsequent motion let$$\displaystyle { K }_{ 1 }$$ and$$\displaystyle { K }_{ 2 }$$ be the maximum kinetic energies of the two coils respectively and let U be the magnitude of maximum potential energy of magnetic interaction of the system of the coils. Choose the correct options.

Question 23 :
&#160;A direct current $$I$$ flows in a long round uniform cylindrical&#160;wire made of paramagnetic material&#160;with susceptibility $$\chi$$.&#160;Find&#160;the surface molecular current $$I_s^\prime$$.

Question 24 :
A permanent magnet has shape of a thin disc with magneticmoment along its axis the radius of the disc is 1 cm. The magnetic field due to it can be assumed to be that due to a molecular current I flowing along the rim of the disc. It $$\bar B$$ at a distance of 10 cm from its centre on the axis is 30$$\mu$$T, find I (approximately).

Question 25 :
The magnetic moment of a dipole is 2 Am$$^{2}$$. Magnetic induction in air at a distance of 10 cm&#160;from the dipole on a line making an angle of $$60^{0}$$&#160;with the axis of dipoles is :<br/>