The magnetic induction at point \(P\), which is \(4\) cm from a long current-carrying wire is \(10^{-8}\) Tesla. What would be the field of induction at a distance of \(12\) cm from the same current?

1.	\(3.33\times 10^{-9}\) Tesla
2.	\(1.11\times 10^{-4}\) Tesla
3.	\(3\times 10^{-3}\) Tesla
4.	\(9\times 10^{-2}\) Tesla

In the figure shown, the magnetic induction at the centre of the arc due to the current in portion AB will be

1. $\frac{{\mathrm{\mu }}_0\mathrm{i}}{\mathrm{r}}$                       3.  $\frac{{\mathrm{\mu }}_0\mathrm{i}}{4\mathrm{r}}$

2. $\frac{{\mathrm{\mu }}_0\mathrm{i}}{2\mathrm{r}}$                       4. Zero

In a current-carrying long solenoid, the field produced does not depend upon:

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 :

1. 0                           2. 45°

3. 60°                       4. 90°

If the current is flowing in the south direction along a power line, then what will be the direction of the magnetic field above the power line (neglecting the earth's field)?

An electron and a proton with equal momentum enter perpendicularly into a uniform magnetic field, then :

Two particles A and B of masses $m_A$ and $m_B$ respectively and having the same type of charge are moving in a plane. A uniform magnetic field exists perpendicular to this plane. The speeds of the particles are $v_A$ and $v_B$ respectively, and the trajectories are as shown in the figure. Then

1. $m_A{v}_A<m_B{v}_B$                              

2. $m_A{v}_A>m_B{v}_B$

3. $m_A<m_B and v_A<v_B$                  

4. $m_A=m_B and v_A=v_B$

An electric current passes through a long straight wire. At a distance 5 cm from the wire, the magnetic field is B. The field at 20 cm from the wire would be :

1. $\frac{\mathrm{B}}{6}$                   

2. $\frac{\mathrm{B}}{4}$

3. $\frac{\mathrm{B}}{3}$                     

4. $\frac{\mathrm{B}}{2}$ 

Two particles X and Y having equal charges, after being accelerated through the same potential difference, enter a region of uniform magnetic field and describes circular path of radius ${\mathrm{R}}_1$ and ${\mathrm{R}}_2$ respectively. The ratio of mass of X to that of Y is :

1.  ${\left(\frac{{\mathrm{R}}_1}{{\mathrm{R}}_2}\right)}^{1/2}$                        2.  $\frac{{\mathrm{R}}_2}{{\mathrm{R}}_1}$

3.  ${\left(\frac{{\mathrm{R}}_1}{{\mathrm{R}}_2}\right)}^2$                            4.  $\frac{{\mathrm{R}}_1}{{\mathrm{R}}_2}$