1. Calculate the frictional force of a crossbar sliding at a constant velocity on two railings. Answer. 1.26 N Given, Crossbar= 256 Ω Distance (separation of railings)= .35 m V (Setup connected to battery)= 12 V B (Magnetic field)= 1.2 T 2. Fb= BIL V=IR 3. The only thing that makes sense would be to do is divide (12 v/ 256Ω) to find I. And then substitute Fb = (1.2 T)(12v/256Ω)(.35 m). But the answer I get is .02 N. Nowhere near the given answer, anything I could be missing??