A charged is moving with constant velocity parallel to a horizontal current carrying long wire. The direction of velocity of that particle and the current are same. If the force acting on the particle are only magnetic force due to wire and gravitational force due to earth, then the particle :

Options

A. must be positively charged
B. must be negatively charged
C. may be positively charged
D. may be neutral

Answer

C

Explanation

magnetic force qvB should be in upward while gravitational force should be in downward direction
If current is in right direction. Then q is +ve (in figure (1))
If current in left direction, then q is -ve in figure (2)