An electron is moving along the positive x-axis. You want to apply a magnetic field for a short time so that the electron may reverse its direction and move parallel to the negative x-axis. This can be done by applying the magnetic field along
(a) y-axis
(b) z-axis
(c) y-axis only
(d) z-axis only
Choose the correct option:
1. (a), (b)
2. (b), (c)
3. (c), (d)
4. (a), (d)

Let \(\overrightarrow{\mathrm{E}}\)and \(\overrightarrow{\mathrm{B}}\)denote electric and magnetic fields in a frame S and \(\overrightarrow{\mathrm{E}}\) and \(\overrightarrow{\mathrm{B}}\) in another frame S' moving with respect to S at a velocity  \(\overrightarrow{\mathrm{v}}\) Two of the following are wrong. Identify them.

(a) B_y’ = B_y +  \(\frac{\mathrm{vE}_{\mathrm{z}}}{\mathrm{c}^{2}}\)
(b) E_y’ = E_y –  \(\frac{\mathrm{vB}_{\mathrm{z}}}{\mathrm{c}^{2}}\)
(c) B’_y = B_y + vE_z
(d) E’_y = E_y + vB_z

Choose the correct option

1. (a), (b)

2. (b), (c)

3. (c), (d)

4. (a), (d)

A vertical wire carries a current in an upward direction. An electron beam sent horizontally towards the wire will be deflected 

1.   towards right

2.   towards left 

3.   upwards

4.   downwards

A current-carrying straight wire is kept along the axis of a circular loop carrying a current. The straight wire

A proton beam is going from north to south and an electron beam is going from south to north. Neglecting the earth's magnetic field, the electron beam will be deflected:

A circular loop is kept in that vertical plane which contains the north-south direction. It carries a current that is towards north at the topmost point. Let A be a point on the axis of the circle to the east of it and B a point on this axis to the west of it. The magnetic field due to the loop

1.  is towards east at A and towards west at B

2.  is towards west at A and towards east at B

3.  is towards east at both A and B

4.  is towards west at both A and B

Consider the situation shown in the figure. The straight wire is fixed but the loop can move under magnetic force. The loop will 

1.  remain stationary

2.  move towards the wire

3.  move away from the wire

4.  rotate about the wire

A charged particle is moved along a magnetic field line. The magnetic force on the particle is:

A moving charge produces:

Two parallel wires carry currents of 20 A and 40 A in opposite directions. Another wire carrying a current antiparallel to 20 A is placed midway between the two wires. The magnetic force on it will be

1.   towards 20 A

2.   towards 40 A

3.   zero

4.   perpendicular to the plane of the currents