speed of light (give me formulation)?

Answer 1

c is exactly 299,792,458 metres per second. The value of c was defined in the 80s as the distance light travels in a vacuum in 1/299,792,458 s. c is slower in air and still slower in other mediums like liquids, crystals, etc.

Answer 2

The speed of light in vacuum is an important physical constant denoted by the letter c for constant or the Latin word celeritas meaning "swiftness".[1] It is the speed of all electromagnetic radiation, including visible light, in a vacuum. More precisely, it is the speed of anything with zero rest mass.


A line showing the speed of light on a scale model of Earth and the Moon, about 1.2 seconds.
In metric units, c is exactly 299,792,458 metres per second (1,079,252,848.8 km/h).[2] The fundamental SI unit of length, the metre, has been defined since October 21, 1983, as the distance light travels in a vacuum in 1/299,792,458 of a second; any increase in the precision of the measurement of the speed of light would refine the definition of the metre, but not alter the numerical value of c. The approximate value of 3×108 m/s is commonly used in rough estimates. In imperial units, the speed of light is about 670,616,629.2 miles per hour or 983,571,056 feet per second, which is about 186,282.397 miles per second, or roughly one foot per nanosecond.

The speed of light when it passes through a transparent or translucent material medium, like glass or air, is slower than its speed in a vacuum. The ratio of c to the observed phase velocity is called the refractive index of the medium. General relativity explains how a gravitational potential can affect the apparent speed of distant light in a vacuum, but locally light in a vacuum always passes an observer at a rate of c.

Answer 3

There is no formulation. The speed of light in a vacuum is a material constant equal to approximately 300,000 km/sec. If you need more precise values, try the damn internet, like the rest of us.

Answer 4

Try using googles ablities a bit more efficiently..
all you had to do to get the exact value is type the letter c into a google window. The first thing that is returned is that value, it also works for a lot of other constants. Just type in the international symbol and the answer pops up immediately
cheers

Answer 5

The speed of light is a measurable quantity - I don't quite understand what you mean by "formulation."
The fact that it is the same for all observers regardless of their relative motion is the basis of relativity theory. In all cases, it can be measured - no need for formulation.