Light. What is light? A light bulb? Energy? Opposite of dark? A feeling? A person? Perhaps light is all of these. Dictionary definitions include electromagnetic radiation that we perceive with the ...

An invisible band of radiation with wavelengths from 400 to 10 nm, ultraviolet (UV) light starts at the end of visible light and ends at the beginning of X-rays. The primary source of ultraviolet ...

All electromagnetic radiation, including light, radio transmission and electricity, travels at approximately 186,000 miles (300,000 kilometers) per second; more than seven times around the equator in ...