Students can explore how a simple electric motor works by doing a series of investigations. This St. Louis motor can be adjusted so students can study the effect of voltage and position of the brushes on the commutator. This model is capable of AC & DC operation. The motor consists of a two pole armature. The brush holder, with binding post terminals, can be rotated for experiments. The permanent magnets, supported by clamps, can be adjusted to the desired location. This apparatus requires AC/DC Power Supply and connecting leads (not included).