Figure shows a metal rod PQ of lenght l,on the smooth horizontal rails AB positioned between the poles of a permanent magnet .the rails ,rod and the magnetic field B are in three mutually perpendicular directions .A galvanometer G connects the rails through a key K .assume the magnetic field to be uniform .given the resistance of the closed loop containing the rod is R.
1. Suppose k is open and the rod is moved with the speed v in the direction shown. Find the polarity and the magnitude of induced emf.
2. With k isbopen and the rod moving uniformly ,there is no net force on the electrons in the rod PQ even though they do experience magnetic force due to the motion of the rod .explain.
3.what is the induced emf in the moving rod if the magnetic field is parallel to the rails instead of being perpendicular.
