We can view this device as a linear generator since application of a mechanical force produces an emf. How about the
opposite: Does the connection of a source produce motion of the bar and, therefore, produce a motor effect? The answer is
yes. To see this, consider Figure 10.3b, which shows the bar and rail discussed above, but now a source V and a resistance
(representing the internal resistance of the source and that of the rails and bar) are connected as shown. We wish to calculate
the force, if any, on the bar. The current in the rail and bar is I ¼ V/R and flows as shown. The force on a current-carrying
conductor in a magnetic field is given by the following relation [see Eq. (9.114)]: