Comprehension Passage
Figure shows a metal rod PQ resting on the rails AB and positioned between the poles of a permanent magnet. The rails, the rod and the magnetic field are in three mutual perpendicular directions. A galvanometer G connects the rails through a switch K. Length of the rod = 15 cm, B = 0.50 T, resistance of the closed loop containing the rod = 180.0 mΩ. Assume the field to be uniform.
The magnetic force experienced by the rod when K is closed will be:
1
7.5 × 10-2 N
2
3.25 × 10-2 N
3
6.45 × 10-2 N
4
3.75 × 10-3 N