A metal bar, mass 0.04kg, resistance 4 Ohms and length 0.5 metres is placed on two frictionless conducting rails in a magnetic field of 0.3 Teslas. The bar is connected to a 36 Volt power source.
a) Calculate the current in the bar.
Well, the Current, I = V/R, I = 36/4
Therefore Current = 9 Amps.
b) Calculate the magnitude of the force which acts on the bar. F = BIl, F = 0.3 x 9 x 0.5
Therefore Force = 1.35 Newtons.
c) If the bar is free to move, and the force is in the appropriate direction, calculate how far it will move along the rails in 0.25 seconds.
[This is the one I'm stuck on.. Not sure how to use weight or time to find the force. We've only been learning about the formula F=BIl sin theta]