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Historically, the symbol V was used as an alternative symbol for the speed of light, introduced by James Clerk Maxwell in 1865. In 1894, Paul Drude redefined c with its modern meaning. Einstein used V in his original German-language papers on special relativity in 1905, but in 1907 he switched to c , which by then had become the standard symbol ...
The speed of light in vacuum is defined to be exactly 299 792 458 m/s (approximately 186,282 miles per second). The fixed value of the speed of light in SI units results from the fact that the metre is now defined in terms of the speed of light. All forms of electromagnetic radiation move at exactly this same speed in vacuum.
In the context of atomic physics, using the atomic units system can be a convenient shortcut, eliminating symbols and numbers and reducing the order of magnitude of most numbers involved. For example, the Hamiltonian operator in the Schrödinger equation for the helium atom with standard quantities, such as when using SI units, is [2]
speed of light (in vacuum) 299,792,458 meters per second (m/s) speed of sound: meter per second (m/s) specific heat capacity: joule per kilogram per kelvin (J⋅kg −1 ⋅K −1) viscous damping coefficient kilogram per second (kg/s) electric displacement field also called the electric flux density coulomb per square meter (C/m 2)
Greek letters are used in mathematics, science, engineering, and other areas where mathematical notation is used as symbols for constants, special functions, and also conventionally for variables representing certain quantities. In these contexts, the capital letters and the small letters represent distinct and unrelated entities.
Symbol Quantity Value [a] [b] Relative standard uncertainty Ref [1]; speed of light in vacuum : 299 792 458 m⋅s −1: 0 [2]Planck constant: 6.626 070 15 × 10 −34 J⋅Hz −1: 0 [3]= / reduced Planck constant
is the speed of light in vacuum. The symbol means that the nucleus is assumed to be infinitely heavy, an improvement of the value can be made using the reduced mass of the atom: = + with the mass of the nucleus. The corrected Rydberg constant is:
This symbol for the photon ... mass than the frequency dependence of the speed of light. ... chemical reactions are provoked only by light of frequency ...