Transformer demonstrates the workings of a transformer, showing that the electrical current actually undergoes two transformations. The first is from electric current to a magnetic field, and the second from a magnetic field to an electric current. The exhibit also shows that only alternating current can be transformed, and 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 DC. power supply, or by leaving the current on and sliding the secondary coil into and out of the primary coil’s magnetic field. We also hang a regular bar magnet on the exhibit which the visitor can move into and out of the secondary coil.