Figure6.20 shows a metal rod PQ resting on the smooth rails AB andpositioned between the poles of a permanent magnet. The rails, therod, and the magnetic field are in three mutual perpendiculardirections. 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 = 9.0mΩ. Assumethe field to be uniform.(a) SupposeK is open and the rod is moved with a speed of 12 cm s−1in the direction shown. Give the polarity and magnitude of theinduced emf.(b) Isthere an excess charge built up at the ends of the rods whenKis open? What if K is closed? (c) With Kopen and the rod moving uniformly, there is nonet force on the electrons in therod PQ even though they do experience magnetic force due to themotion of the rod. Explain.(d) Whatis the retarding force on the rod when K is closed?(e) Howmuch power is required (by an external agent) to keep the rod movingat the same speed (=12 cm s−1)when K is closed? How much power is required when K is open?(f) Howmuch power is dissipated as heat in the closed circuit?Whatis the source of this power?(g) Whatis the induced emf in the moving rod if the magnetic field isparallel to the rails instead of being perpendicular?