aIn the 1860s, James Clerk Maxwell (1831–1879) conceptualized electromagnetic
radiation (EMR) as an electromagnetic wave that travels through space at the
speed of light, c, which is 3 x 108 meters per second.
The electromagnetic wave consists of two fluctuating fields - one electric and the
other magnetic. The two vectors are at right angles (orthogonal) to one another,
and both are perpendicular to the direction of travel.