This problem explores how a current$-$carrying wire can be accelerated by a magnetic field. You will use the ideas of magnetic flux and the EMF due to change of flux through a loop.

A conducting rod of mass m is free to slide on two parallel rails with negligible friction. At the right end of the rails, a battery with emf V in series with a resistor of resistance R makes a closed circuit together with the rails and the rod. The rails and the rod are taken to be perfect conductors. The rails extend to infinity on the left.

V

$-$

R

AHW $14$

rod

There is a uniform magnetic field of magnitude B$,$ pervading all space, perpendicular to the plane of rod and rails. The rod is released from rest, and it is observed that it accelerates to the left. In what direction does the magnetic field point?