In the arrangement shown in the figure,
the resistor is 7 Ω and a 6 T magnetic field
is directed into the paper. The separation
between the rails is 5 m .
An applied force moves the bar to the left
at a constant speed of 4 m/s. At what rate is energy dissipated in the
resistor? Assume the bar and rails have negligible resistance and friction. Neglect the mass
of the bar.
Answer in units of W.