Electricity and Magnetism

Adjustable Plaything

This exhibit has a counter, a vibrating steel strap, and an electromagnet. Contacts on either side of the metal strap either turn on the electromagnet (attracting the steel strap) or cause the counter to increment by one. By carefully adjusting the spacing of the electrical contacts near the steel strap, an oscillation can be created as the strap alternately makes and breaks its electromagnet contact. A sliding weight can be attached to the steel strap that will change the frequency of vibration.