History of EM waves

William Gilbert

(1544-1603) systematically studied magnetism and coined the term "electricus" to describe materials that attracted small objects; This laid the foundation for the study of electricity and magnetism as distinct phenomena

Hans Christian Orsted

(1777-1851) while performing experiments with electric currents, he noticed that a magnetic needle moved when an electric current passed through a wire nearby; he discorvered that an electric current is surrounded by magnetic field; he discovered that an electric current is surrounded by magnetic field; a current-carrying wire produces a magnetic field.

Michael Faraday

(1830s-1850s) he discovered that a moving wire through a magnetic field could produce an electric current.

Electromagnetic Induction

when a wire is moved through a magnetic field, a current is generated in the wire.

Joseph Henry

(1797-1878) independently discovered the phenomenon of electromagnetic induction, similar to Faraday's work.

Induced current

Current produced by magnetic field.

James Clack Maxwell

(1831-1879) the culmination of previous discoveries in electromagnetism; he discovered a scientific theory; he noticed that electrical fields and magnetic fields can couple together to form electromagnetic waves; he formulated the famous Maxwell's equation; describe how electric and magnetic fields interact and how they move through space as waves; the key idea is that electromagnetic waves travel at the speed of light, meaning light itself is an electromagnetic wave.

Heinrich Hertz

(1857-1894) his experiment confirmed the existence of electromagnetic waves predicted by Maxwell; He applied Maxwell's theory to the production and reception of radio waves; He proved the existence of radiowaves; he used two rods that served as the receiver and a spark gap transmitter; when the waves picked up, a corresponding spark would jump; he showed that these signals possess all the properties of electromagnetic waves

1 cycle/second (Hertz)

Unit of frequency of radio wave