$5$

An $L=4\mathrm{.}8cm$ wire is moving to the right at a speed of $v=8\frac{m}{s}$ across two parallel wire rails that are connected on the left side, as shown in the figure. The whole apparatus is immersed in a uniform magnetic field that has a magnitude of $B=6\mathrm{.}6T$ and is directed into the screen.

If the moving wire and the rails have a combined total resistance of $6\mathrm{.}2,$ what applied force $F$ would be required to keep the wire moving at the given velocity? Assume that there is no friction between the moving wire and the rails.

Answer: