A current-carrying closed Loop in the form of a right isosceles triangle ABC is placed in xy plane in a uniform magnetic field acting along the y-axis as shown in the figure. If the magnetic force on the arm AC is $\overrightarrow{F}$, then force on the arm BC and AB are respectively

(1) zero, zero

(2) $-\overrightarrow{F} and zero$

(3) $\overrightarrow{F} and -\overrightarrow{F}$

(4) $\overrightarrow{F} and zero$

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

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.  $\frac{{\mathrm{Ma}}_0}{\mathrm{e}}\mathrm{west}, \frac{{\mathrm{Ma}}_0}{{\mathrm{ev}}_0}\mathrm{up}$

2.  $\frac{{\mathrm{Ma}}_0}{\mathrm{e}}\mathrm{west}, \frac{2{\mathrm{Ma}}_0}{{\mathrm{ev}}_0}\mathrm{down}$

3.  $\frac{{\mathrm{Ma}}_0}{\mathrm{e}}\mathrm{east}, \frac{2{\mathrm{Ma}}_0}{{\mathrm{ev}}_0}down$

4.  $\frac{{\mathrm{Ma}}_0}{\mathrm{e}}\mathrm{east}, \frac{2{\mathrm{Ma}}_0}{{\mathrm{ev}}_0}up$

If the planes of two identical concentric coils are the perpendicular and magnetic moment of each coil is M, then the resultant magnetic moment of the two coil system is 

1.  M

2.  $\sqrt{2}\mathrm{M}$

3.  3M

4.  2M

Which of the following graph 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 positively charged particle falls vertically downwards. The horizontal component of the earth's magnetic field will deflect it towards:

(1) east

(2) west

(3) north

(4) south

The magnetic dipole moment of the given loop is:

1.  $\frac{5}{2}{\mathrm{\pi R}}^2\mathrm{I}$

2.  $3{\mathrm{\pi R}}^2\mathrm{I}$

3.  $\frac{3}{2}{\mathrm{\pi R}}^2\mathrm{I}$

4.  $5{\mathrm{\pi R}}^2\mathrm{I}$

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

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.  $\frac{2\mathrm{qB}\left(\mathrm{b} - \mathrm{a}\right)}{\mathrm{m}}$

2.  $\frac{\mathrm{qB}\left(\mathrm{b} + \mathrm{a}\right)}{2\mathrm{m}}$

3.  $\frac{\mathrm{qB}\left(\mathrm{b} - \mathrm{a}\right)}{\mathrm{m}}$

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