1. Recall the induction example from lecture in which a resistanceless metal bar with length & slides to the right on metal rails with a constant speed v and the metal rails are connected to a resistor R. The entire system is placed in a uniform constant magnetic field with magnitude B pointing out of the screen. Ꭱ . v Use Lenz's last to determine the direction in which the induced current flows. b) In lecture we simply assumed the bar moves with constant speed v. Show that an external force is needed to ensure the bar travels right with constant speed and determine the magnitude of this force (Hint: there will be a magnetic force on the bar due to the current flowing through it). c*) Show that the power dissipated in the resistor equals the rate at which work is done on the bar by the external force.

1. Recall the induction example from lecture in which a resistanceless metal bar with length & slides to the right on metal rails with a constant speed v and the metal rails are connected to a resistor R. The entire system is placed in a uniform constant magnetic field with magnitude B pointing out of the screen. Ꭱ . v Use Lenz's last to determine the direction in which the induced current flows. b) In lecture we simply assumed the bar moves with constant speed v. Show that an external force is needed to ensure the bar travels right with constant speed and determine the magnitude of this force (Hint: there will be a magnetic force on the bar due to the current flowing through it). c*) Show that the power dissipated in the resistor equals the rate at which work is done on the bar by the external force.