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

1.	voltage sensitivity becomes double.
2.	current sensitivity becomes double.
3.	voltage sensitivity becomes half.
4.	current sensitivity remains the same.

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

An electron and a proton are revolving around a common centre O in two coplanar circular paths as shown in the figure with a time period of rotation of 1 s and 2 s, respectively. What will be the net magnetic field at O?

1. \(\frac{\mu _{0}e}{\pi }\) tesla.
2. \(\frac{\mu _{0}e}{2}\) tesla.
3. \(2\mu _{0}e\) tesla.
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?

On connecting a shunt of \(10 ~ \Omega,\) the deflection in a moving coil galvanometer falls from 40 divisions to 6 divisions. What is the resistance of the galvanometer?

Which one of the following expressions represents Biot-Savart's law? Symbols have their usual meanings.

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)