The VISIBLE SPECTRUM contains all the colors between infrared and ultraviolet. INFRA-RED
and ULTRA-VIOLET are invisible to the human eye.
The PRIMARY COLORS of light are red, green, and blue. These primaries can be mixed to make
any color between red and violet. If the three colors are mixed equally, they produce white light.
The COMPLEMENTARY COLORS of light are magenta, yellow, and cyan. They are produced
by mixing any two of the primary colors together in overlapping beams.
The SPEED OF LIGHT in empty space is considered to be 186,000 miles per second (or
300,000,000 meters per second). This speed varies in different mediums, but the constant of 186,000
miles per second is always used as the speed of light.
The ELECTROMAGNETIC SPECTRUM is the complete range of electromagnetic frequencies
from 3 kHz to beyond 300,000 THz. Audio frequencies (15 Hz-20 kHz) are not electromagnetic energy
and are not included in the electromagnetic spectrum.