For the magnetic field to be maximum due to a small element of current-carrying conductor at a point, the angle between the element and the line joining the element to the given point must be:

1. 0°                           
2. 90°
3. 180°                        
4. 45°

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

Cyclotron cannot be used to accelerate

1. Electrons                       

2. Neutrons

3. Positive ions                   

4. Both (1) and (2)

 The dimension of the magnetic field intensity B is:

1.  ${\mathrm{MLT}}^{-2}{\mathrm{A}}^{-1}$                   

2.  ${\mathrm{MT}}^{-2}{\mathrm{A}}^{-1}$

3.  ${\mathrm{ML}}^2{\mathrm{TA}}^{-2}$                       

4.  ${\mathrm{M}}^2{\mathrm{LT}}^{-2}{\mathrm{A}}^{-1}$

An $\mathrm{\alpha }-$ particle travels in a circular path of radius 0.45 m in a magnetic field $\mathrm{B}=1.2 Wb\mathit{/}{m}^{\mathit{2}}$ with a speed of $2.6\times {10}^7 m\mathit{/}sec$ . The period of revolution of the $\mathrm{\alpha }-$ particle is :

1.  $1.1\times {10}^{-5 }$ sec          2.  $1.1\times {10}^{-6}$ sec

3.  $1.1\times {10}^{-7}$ sec            4.  $1.1\times {10}^{-8}$ sec

A rectangular loop carrying a current i is situated near a long straight wire such that the wire is parallel to the one of the sides of the loop and is in the plane of the loop. If a steady current I is established in wire as shown in figure, the loop will

1. Rotate about an axis parallel to the wire

2. Move away from the wire or towards right

3. Move towards the wire

4. Remain stationary

To make the field radial in a moving coil galvanometer :

1. The number of turns in the coil is increased

2. Magnet is taken in the form of horse-shoe

3. Poles are cylindrically cut

4. The coil is wounded on the aluminum frame

A proton of mass $1.67\times {10}^{-27}kg$ and charge $1.6\times {10}^{-19}C$ is projected with a speed of $2\times {10}^{6}m/s$ at an angle of $60°$ to the X-axis. If a uniform magnetic field of 0.104 Tesla is applied along Y-axis, the path of the proton is:

1. A circle of radius = 0.2 m and time period $\mathrm{\pi }\times {10}^{-7}\mathrm{s}$

2. A circle of radius = 0.1 m and time period $2\mathrm{\pi }\times {10}^{-7}\mathrm{s}$ 

3. A helix of radius = 0.1 m and time period $2\mathrm{\pi }\times {10}^{-7}\mathrm{s}$

4. A helix of radius = 0.2 m and time period $4\mathrm{\pi }\times {10}^{-7}\mathrm{s}$

An electric field of 1500 V / m and a magnetic field of 0.40 weber / $mete{r}^2$ act on a moving electron. The minimum uniform speed along a straight line the electron could have is

1. $1.6\times {10}^{15}m/s$                         

2. $6\times {10}^{-16}m/s$

3. $3.75\times {10}^{3}m/s$                         

4. $3.75\times {10}^{2}m/s$