A special magnet (pole on the long side) is placed between two brass bars. A current source is attached to the bars and a brass rod is placed between them. The current through the rod is acted on by the magnetic field and caused to roll across the overhead projector.
Questions:
Given the direction of travel and the polarity of the applied voltage, in which way is the magnetic field directed?
or
Given the magnetic field is upward, and the current flows from left to right, which way will the bar roll?
