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  2. Speed of light - Wikipedia

    en.wikipedia.org/wiki/Speed_of_Light

    In such a theory, its speed would depend on its frequency, and the invariant speed c of special relativity would then be the upper limit of the speed of light in vacuum. [32] No variation of the speed of light with frequency has been observed in rigorous testing, putting stringent limits on the mass of the photon. [ 59 ]

  3. 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.

  4. Wavelength - Wikipedia

    en.wikipedia.org/wiki/Wavelength

    In a dispersive medium, the phase speed itself depends upon the frequency of the wave, making the relationship between wavelength and frequency nonlinear. In the case of electromagnetic radiation—such as light—in free space, the phase speed is the speed of light, about 3 × 10 8 m/s.

  5. Relativistic Doppler effect - Wikipedia

    en.wikipedia.org/wiki/Relativistic_Doppler_effect

    The next wavefront is then at a distance = / away from the receiver (where is the wavelength, is the frequency of the waves that the source emits, and is the speed of light). The wavefront moves with speed , but at the same time the receiver moves away with speed during a time ,, which is the period of light waves impinging on the receiver, as ...

  6. Electromagnetic radiation - Wikipedia

    en.wikipedia.org/wiki/Electromagnetic_radiation

    As a wave, light is characterized by a velocity (the speed of light), wavelength, and frequency. As particles, light is a stream of photons . Each has an energy related to the frequency of the wave given by Planck's relation E = hf , where E is the energy of the photon, h is the Planck constant , 6.626 × 10 −34 J·s, and f is the frequency ...

  7. Photon energy - Wikipedia

    en.wikipedia.org/wiki/Photon_energy

    is frequency [2] 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

  8. Wave equation - Wikipedia

    en.wikipedia.org/wiki/Wave_equation

    The wave equation is a second-order linear partial differential equation for the description of waves or standing wave fields such as mechanical waves (e.g. water waves, sound waves and seismic waves) or electromagnetic waves (including light waves).

  9. Dispersion relation - Wikipedia

    en.wikipedia.org/wiki/Dispersion_relation

    The equation says the matter wave frequency in vacuum varies with wavenumber (= /) in the non-relativistic approximation. The variation has two parts: a constant part due to the de Broglie frequency of the rest mass ( ℏ ω 0 = m 0 c 2 {\displaystyle \hbar \omega _{0}=m_{0}c^{2}} ) and a quadratic part due to kinetic energy.