Level: Elementary to H.S.
Time involvement: 10-20 minutes.
Like the force of gravity, magnetism is invisible but very real. This lesson combines basic magnet facts like the North and South “pole” characteristics, and attraction and repulsion behavior with a fascinating application in a small electric motor. The motor is a small Cub Scout project that clearly shows the wire windings of the field and armature. The commutator, which is actually an electrical switch to reverse the current and thus the poles of the spinning armature, is clearly visible. A 6-volt battery nicely powers the motor. The open frame construction makes the components and operation easy to grasp.
Discussion: The Earth itself is a giant magnet that makes possible the use of a magnetic compass to navigate across vast oceans. Door latches, and electrical devices often use magnetic principles. Michael Faraday, the famous British scientist, made the connection between electricity and magnetism. Electric power plants use the energy of burning coal or gas to run steam turbines. The turbines are connected to huge generators using the principle of a moving magnetic field to produce electricity. This demonstration opens young minds to questions about lightening, static electricity, and safety.
Notes: Although plans are not available for the motor the construction is fairly simple but will require some tool knowledge and patience.