PHYSICS · Subjective · AP · Physics 2: Algebra-based · Magnetism and Electromagnetism · Magnetism and Electromagnetism
Problem
During a school project, a 0.40m long aluminium rod is placed between the pole pieces of a horseshoe magnet. The uniform magnetic field is horizontal and the current through the rod can be varied.
(i) When the rod is held exactly parallel to the magnetic field, it does not experience any noticeable mechanical effect. Explain why.
(ii) When the same rod is turned so that it is exactly perpendicular to the magnetic field, it suddenly jumps side-ways. Explain the reason for this behaviour and state the rule that gives the direction of the jump.
(iii) Starting from the parallel position, determine the smallest angle through which the rod must be rotated so that the magnitude of the magnetic force on it reaches at least 50% of its maximum possible value. Show your reasoning.