Dictionary of Environmental Health
The distance covered by the electromagnetic radiation (of which visible light is a part) per unit time. The speed of light was once thought to be a universal constant, but it is now known that this contention is not absolutely true.
For all practical purposes however the speed of light is quoted as being 299,796 km/sec. (equivalent to 186,293 miles/sec.).
This is the complete article, containing 63 words
(approx. 1 page at 300 words per page).
View More Summaries on Speed of light
