Electricity & Magnetism


This exhibit demonstrates the workings of a TRANSFORMER. Many people believe that you simply put electricity into one end of a transformer and take it out of the other end. This exhibit shows that the electric current actually undergoes two transformations: first from electric current to a magnetic field, and then back again from a magnetic field to an electric current. The exhibit also shows that one can only transform alternating current, not direct current, since the secondary coil only responds to a changing magnetic field. The exhibit allows the visitor to change the magnetic field by either changing the current in the primary coil with a lever that controls the D.C. power supply, or by leaving the current on and sliding the secondary coil into and out of the primary coil's magnetic field. A regular bar magnet is hung on the exhibit which the visitor can move into and out of the secondary coil, resulting in the same response as if the primary coil was being used. This demonstrates the equivalence of a magnetic field produced by a current running in a coil and that of a permanent magnet.