If the magnetic field at the centre of the circular coil is B₀, then what is the distance on its axis from the centre of the coil where  \(B_x=\frac{B_0}{8}~?\)
(R= radius of the coil)

1.	\(R \over 3\)	2.	\(\sqrt{3}R\)
3.	\(R \over \sqrt3\)	4.	\(R \over 2\)

What happens when the number of turns in a galvanometer is doubled?

The two parts of the loop are circles of radii 2a and a, respectively, and carry the same current i as shown in the given figure. What is the magnitude of the dipole moment of the current loop?

1. $5{\mathrm{\pi a}}^2$ $\mathrm{i}$

2. $4{\mathrm{\pi a}}^2$ $\mathrm{i}$

3. $3{\mathrm{\pi a}}^2$ $\mathrm{i}$

4. Zero

What is the magnetic moment of the following current loop?
 
1. $24$ $A{m}^2$

2. $12$ $A{m}^2$

3. $6$ $A{m}^2$

4. Zero

As indicated, a long, straight conductor XY carrying a current i₁ is placed antiparallel to a conductor AB of length l carrying a current i₂. How much of a force is acting on AB?

1. ${\mu }_0{i}_1{i}_2$

2.  $\frac{{\mu }_0{i}_1{i}_2}{\mathrm{\pi }}$

3. $\frac{{\mu }_0{i}_1{i}_2}{2\mathrm{\pi }}$

4. $2{\mu }_0{i}_1{i}_2$

If a long hollow copper pipe carries a direct current along its length, then the magnetic field associated with the current will be:

Magnetic field at the outer surface of long hollow cylindrical shells of radius R and carrying current I is B. What is the magnetic field at a distance of $\frac{3R}{2}$ from the axis of the cylindrical shell?

A charged particle is projected through a region in a gravity-free space. If it passes through the region with constant speed, then the region may have:
1. \(\vec{E}=0, \vec{B} \neq 0\)
2. \(\vec{E} \neq 0, \vec{B} \neq 0\)
3. \(\vec{E} \neq 0, \vec{B}=0\)
4. Both (1) & (2)

A neutron, a proton, an electron and an \(\alpha\text-\)particle enter a region of the uniform magnetic field with the same velocity. The magnetic field is perpendicular and directed into the plane of the paper. The tracks of the particles are labelled in the figure. Which track will the \(\alpha\text-\)particle follow?
             

The resistances of three parts of a circular loop are as shown in the figure. What will be the magnetic field at the centre of O 
(current enters at A and leaves at B and C as shown)?

1.  $\frac{{\mathrm{\mu }}_0\mathrm{I}}{6\mathrm{a}}$

2.  $\frac{{\mathrm{\mu }}_0\mathrm{I}}{3\mathrm{a}}$

3.  $\frac{2{\mathrm{\mu }}_0\mathrm{I}}{3\mathrm{a}}$

4.  0