The wire carries a current towards the east . The magnetic field will make circular path around the wire in clockwise direction so at a point just south of wire , magnetic field will be into the plane of paper containing wire. If we take east as x -axes , north as y axes then out of plane will form z axes. Hence direction of magnetic field will be - z direction .
Magnetic field can be represented as - B k
Proton is moving towards east ie in + x direction so it can be represented as follows
velocity = V i
Force F = q( V i x -B k)
= ( BqV) j or + ve j direction or along north direction
So direction of force will be along north direction.
