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Line 1: − + − :λ = c / f+ − ([[wavelength]] of an electromagnetic wave in vacuum = the speed of light divided by the wave's frequency).+ + + + + + +
Improved formatting of formula
The '''speed of light''' in a vacuum (observed to be the same for all inertial observers, a fact which gave rise to the [[Special Theory of Relativity]]) is 299,792,458 meters per second (approximately 186,282.3 miles per second). This is the speed '''by definition'''. It is used to give the [[SI]] definition of the meter, in terms of the SI definition of the second, which is derived from the Cesium clock.
The '''speed of light''' in a vacuum (observed to be the same for all inertial observers, a fact which gave rise to the [[Special Theory of Relativity]]) is 299,792,458 meters per second (approximately 186,282.3 miles per second). This is the speed '''by definition'''. It is used to give the [[SI]] definition of the meter, in terms of the SI definition of the second, which is derived from the Cesium clock.
In physics, it is often represented in equations by the letter '''c,''' as in
In physics, it is often represented in equations by the letter <math> c </math>.
<math> \lambda f =c </math>
Where
:<math> \lambda </math> is the [[wavelength]] of an electromagntic wave in vacuum
:<math> f</math> is the frequency of the wave
:<math> c </math> is the speed of light
The speed of light is about one foot per nanosecond. The late computer pioneer Admiral Grace Hopper was fond of keeping foot-long lengths of wire in her purse; she used them as props for her talks, referring to them as "nanoseconds," and using them to explain how the speed of light set limitations on [[computing]] systems: no signal could possibly propagate in any wire faster than the speed of light.<ref>Chiarella, Donald Joseph Gray (2002), ''Life in God's Management Corps,'' [http://books.google.com/books?vid=ISBN0595256430&id=VhM9jDwbywUC&pg=PA14&lpg=PA14&ots=ZXHirs9jQI&dq=grace+hopper+nanosecond&ie=ISO-8859-1&sig=XmbYtV2laxCMIKMLzR1eXHP1Eok p. 14]</ref>
The speed of light is about one foot per nanosecond. The late computer pioneer Admiral Grace Hopper was fond of keeping foot-long lengths of wire in her purse; she used them as props for her talks, referring to them as "nanoseconds," and using them to explain how the speed of light set limitations on [[computing]] systems: no signal could possibly propagate in any wire faster than the speed of light.<ref>Chiarella, Donald Joseph Gray (2002), ''Life in God's Management Corps,'' [http://books.google.com/books?vid=ISBN0595256430&id=VhM9jDwbywUC&pg=PA14&lpg=PA14&ots=ZXHirs9jQI&dq=grace+hopper+nanosecond&ie=ISO-8859-1&sig=XmbYtV2laxCMIKMLzR1eXHP1Eok p. 14]</ref>
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