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2. Speed of light - Wikipedia

   en.wikipedia.org/wiki/Speed_of_Light

   Sometimes c is used for the speed of waves in any material medium, and c 0 for the speed of light in vacuum. [10] This subscripted notation, which is endorsed in official SI literature, [ 11 ] has the same form as related electromagnetic constants: namely, μ 0 for the vacuum permeability or magnetic constant, ε 0 for the vacuum permittivity ...

3. Photon energy - Wikipedia

   en.wikipedia.org/wiki/Photon_energy

   This equation is known as the Planck relation. Additionally, using equation f = c/λ, = where E is the photon's energy; λ is the photon's wavelength; c is the speed of light in vacuum; h is the Planck constant; The photon energy at 1 Hz is equal to 6.626 070 15 × 10 −34 J, which is equal to 4.135 667 697 × 10 −15 eV.

4. List of common physics notations - Wikipedia

   en.wikipedia.org/wiki/List_of_common_physics...

   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)

5. Electromagnetic wave equation - Wikipedia

   en.wikipedia.org/wiki/Electromagnetic_wave_equation

   is the speed of light (i.e. phase velocity) in a medium with permeability μ, and permittivity ε, and ∇ 2 is the Laplace operator. In a vacuum, v ph = c 0 = 299 792 458 m/s, a fundamental physical constant. [1] The electromagnetic wave equation derives from Maxwell's equations.

6. Maxwell's equations - Wikipedia

   en.wikipedia.org/wiki/Maxwell's_equations

   The equations simplify slightly when a system of quantities is chosen in the speed of light, c, is used for nondimensionalization, so that, for example, seconds and lightseconds are interchangeable, and c = 1. Further changes are possible by absorbing factors of 4π.

7. Fizeau's measurement of the speed of light in air - Wikipedia

   en.wikipedia.org/wiki/Fizeau's_measurement_of_the...

   At 3 times the speed it was again eclipsed. [3] [4] Given the rotational speed of the wheel and the distance between the wheel and the mirror, Fizeau was able to calculate a value of 2 × 8633m × 720 × 25.2/s = 313,274,304 m/s for the speed of light. Fizeau's value for the speed of light was 4.5% too high. [5] The correct value is 299,792,458 ...

8. Refractive index - Wikipedia

   en.wikipedia.org/wiki/Refractive_index

   The absolute refractive index n of an optical medium is defined as the ratio of the speed of light in vacuum, c = 299 792 458 m/s, and the phase velocity v of light in the medium, =. Since c is constant, n is inversely proportional to v : n ∝ 1 v . {\displaystyle n\propto {\frac {1}{v}}.}

9. Fine-structure constant - Wikipedia

   en.wikipedia.org/wiki/Fine-structure_constant

   c is the speed of light (299 792 458 m⋅s −1 ‍ [8]); ε 0 is the electric constant ( 8.854 187 8188 (14) × 10 −12 F⋅m −1 ‍ [ 9 ] ). Since the 2019 revision of the SI , the only quantity in this list that does not have an exact value in SI units is the electric constant (vacuum permittivity).