Ionized hydrogen atoms and \(\alpha\text-\)particles with the same momenta enter perpendicular to a constant magnetic field, \(B\). The ratio of their path radii \(r_{H}:r_\alpha\) will be:

1.	\(1:4\)	2.	\(2:1\)
3.	\(1:2\)	4.	\(4:1\)

A cylindrical conductor of radius \(R\) is carrying a constant current. The plot of the magnitude of the magnetic field \(B\) with the distance \(d\) from the centre of the conductor is correctly represented by the figure:

1.		2.
3.		4.

A millivoltmeter of \(25~\text{mV}\) range is to be converted into an ammeter of \(25~\text{A}\) range. The value (in ohm) of the necessary shunt will be:
1. \(0.001\)
2. \(0.01\)
3. \(1\)
4. \(0.05\)

Moving perpendicular to field \(B\), a proton and an alpha particle both enter an area of uniform magnetic field \(B\). If the kinetic energy of the proton is \(1~\text{MeV}\) and the radius of the circular orbits for both particles is equal, the energy of the alpha particle will be:
1. \(4~\text{MeV}\)
2. \(0.5~\text{MeV}\)
3. \(1.5~\text{MeV}\)
4. \(1~\text{MeV}\)

If a square loop \({ABCD}\) carrying a current \(i\) is placed near and coplanar with a long straight conductor \({XY}\) carrying a current \(I,\) what will be the net force on the loop?
                  
1. \(\dfrac{\mu_0Ii}{2\pi}\)
2. \(\dfrac{2\mu_0IiL}{3\pi}\)
3. \(\dfrac{\mu_0IiL}{2\pi}\)
4. \(\dfrac{2\mu_0Ii}{3\pi}\)

The current sensitivity of a moving coil galvanometer is \(5~\text{div/mA}\) and its voltage sensitivity (angular deflection per unit voltage applied) is \(20~\text{div/V}.\) The resistance of the galvanometer is: 
1. \(40~\Omega\)
2. \(25~\Omega\)
3. \(250~\Omega\)
4. \(500~\Omega\)

An arrangement of three parallel straight wires placed perpendicular to the plane of paper carrying the same current in the same direction is shown in the figure. The magnitude of force per unit length on the middle wire \(B\) is given by:
    
1. \(\dfrac{\mu_0i^2}{2\pi d}\)
2. \(\dfrac{2\mu_0i^2}{\pi d}\)
3. \(\dfrac{\sqrt{2}\mu_0i^2}{\pi d}\)
4. \(\dfrac{\mu_0i^2}{\sqrt{2}\pi d}\)

A \(250\) turn rectangular coil of length \(2.1\) cm and width \(1.25\) cm carries a current of \(85~\mu\text{A}\) and subjected to the magnetic field of strength \(0.85~\text{T}\). Work done for rotating the coil by \(180^\circ\) against the torque is:
1. \(4.55~\mu\text{J} \)
2. \(2.3~\mu\text{J} \)
3. \(1.15~\mu\text{J} \)
4. \(9.4~\mu\text{J} \)