Two parallel conducting rails separated by a distance I are fixed on a plane surface, inclined at an angle `alpha` to the horizontal as shown in figure-5.336. Rails are connected at the bottom by a resistance R. A copper rod of mass in slides without friction on the rails due to gravity. A uniform vertical field B exists throughout the region. Find the steady state velocity of the rod. Show that the rate at which thermal energy is produced in the circuit is equal to the rate at which rod is losing gravitational potential energy. What will happen if the direction of B is reversed?