Figure 6.20 shows a metal rod PQ resting on the smooth 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 = 9.0 mOmega` Assume the field to be uniform. Suppose K is open and the rod is moved with a speed of `12 cm s^-1` in the direction shown. Give the polarity and magnitude of the induced emf. :