INVENTIONS

Speakers

the electromagnet and the speaker cone can be made to back and forth. If the variation of the electric current is at the same frequencies of sound waves, the resulting vibration of the speaker cone will create sound waves, including that from voice and music.

Relay Switches

The basic functioning of an electromagnetic relay involves generating a magnetic field in an iron core by the passage of an electric current through a coil of wire wound around it. When an electric current passes through the coil, the magnetic field generated makes or breaks of circuit.