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 power dissipated as heat in the closed circuit is:
1
1.5 × 10-3 W
2
3 × 10-3 W
3
9.0 × 10-3 W
4
4.5 × 10-4 W