Which of the following graphs correctly represents the variation of magnetic field induction with distance due to a thin wire carrying current?

1.		2.
3.		4.

When an electron enters perpendicularly in a magnetic field with velocity v, time period of its revolution is T. If it enters in the same magnetic field with a velocity 2v, then its time period will be:

1.  2T

2.  4T

3.  $\frac{\mathrm{T}}{2}$

4.   T

A uniform electric field and a uniform magnetic field are acting in the same direction in a certain region. If a proton is projected in this region such that its velocity is pointed along the direction of fields, then the proton :

1.  will turn towards the left of the direction of motion

2.  will turn towards the right of the direction of motion

3.  will speed up

4.  will slow down

What is the magnetic dipole moment of the given loop?

The figure shows a particle of charge q and mass m moving with velocity v along the x-axis enters a region of the uniform magnetic field. The minimum value of v so that the charge q is deflected by an angle $30°$ is

1.  $\frac{2\mathrm{qB}\left(\mathrm{b}<mspace\; width="1em"></mspace>-<mspace\; width="1em"></mspace>\mathrm{a}\right)}{\mathrm{m}}<mspace\; width="1em"></mspace>$

2.  $\frac{\mathrm{qB}\left(\mathrm{b}<mspace\; width="1em"></mspace>+<mspace\; width="1em"></mspace>\mathrm{a}\right)}{2\mathrm{m}}<mspace\; width="1em"></mspace>$

3.  $\frac{\mathrm{qB}\left(\mathrm{b}<mspace\; width="1em"></mspace>-<mspace\; width="1em"></mspace>\mathrm{a}\right)}{\mathrm{m}}<mspace\; width="1em"></mspace>$

4.  $\frac{\mathrm{qBb}}{2\mathrm{m}}$

The magnetic field at center due to the orbital motion of the electron in the hydrogen atom is :

1.  12.5 tesla

2.  5 tesla

3.  24 tesla

4.  1 tesla

A positively charged particle descends vertically. In which direction will the horizontal component of the earth's magnetic field deflect?

1. east

2. west

3. north

4. south

When a proton is released from rest in a room, it starts with an initial acceleration ${\mathrm{a}}_0$ towards the east. When it is projected towards the north with a speed ${\mathrm{v}}_0$, it moves with initial acceleration $3{\mathrm{a}}_0$ towards east. The electric and magnetic fields in the room are -

1.  $\frac{{\mathrm{Ma}}_0}{\mathrm{e}}\mathrm{west},<mspace\; width="1em"></mspace>\frac{{\mathrm{Ma}}_0}{{\mathrm{ev}}_0}\mathrm{up}$

2.  $\frac{{\mathrm{Ma}}_0}{\mathrm{e}}\mathrm{west},<mspace\; width="1em"></mspace>\frac{2{\mathrm{Ma}}_0}{{\mathrm{ev}}_0}\mathrm{down}$

3.  $\frac{{\mathrm{Ma}}_0}{\mathrm{e}}\mathrm{east},<mspace\; width="1em"></mspace>\frac{2{\mathrm{Ma}}_0}{{\mathrm{ev}}_0}down$

4.  $\frac{{\mathrm{Ma}}_0}{\mathrm{e}}\mathrm{east},<mspace\; width="1em"></mspace>\frac{2{\mathrm{Ma}}_0}{{\mathrm{ev}}_0}up$