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  2. Mass–energy equivalence - Wikipedia

    en.wikipedia.org/wiki/Mass–energy_equivalence

    The formula defines the energy E of a particle in its rest frame as the product of mass (m) with the speed of light squared (c 2). Because the speed of light is a large number in everyday units (approximately 300 000 km/s or 186 000 mi/s), the formula implies that a small amount of "rest mass", measured when the system is at rest, corresponds ...

  3. Planck relation - Wikipedia

    en.wikipedia.org/wiki/Planck_relation

    The Planck relation [1] [2] [3] (referred to as Planck's energy–frequency relation, [4] the Planck–Einstein relation, [5] Planck equation, [6] and Planck formula, [7] though the latter might also refer to Planck's law [8] [9]) is a fundamental equation in quantum mechanics which states that the energy E of a photon, known as photon energy, is proportional to its frequency ν: =.

  4. Energy–momentum relation - Wikipedia

    en.wikipedia.org/wiki/Energy–momentum_relation

    In physics, the energy–momentum relation, or relativistic dispersion relation, is the relativistic equation relating total energy (which is also called relativistic energy) to invariant mass (which is also called rest mass) and momentum. It is the extension of mass–energy equivalence for bodies or systems with non-zero momentum.

  5. Speed of light - Wikipedia

    en.wikipedia.org/wiki/Speed_of_Light

    v. t. e. The speed of light in vacuum, commonly denoted c, is a universal physical constant that is exactly equal to 299,792,458 metres per second (approximately 300,000 kilometres per second; 186,000 miles per second; 671 million miles per hour).

  6. Planck constant - Wikipedia

    en.wikipedia.org/wiki/Planck_constant

    The Planck constant, or Planck's constant, denoted by , [1] is a fundamental physical constant [1] of foundational importance in quantum mechanics: a photon's energy is equal to its frequency multiplied by the Planck constant, and the wavelength of a matter wave equals the Planck constant divided by the associated particle momentum.

  7. Compton wavelength - Wikipedia

    en.wikipedia.org/wiki/Compton_wavelength

    Compton wavelength. The Compton wavelength is a quantum mechanical property of a particle, defined as the wavelength of a photon whose energy is the same as the rest energy of that particle (see mass–energy equivalence). It was introduced by Arthur Compton in 1923 in his explanation of the scattering of photons by electrons (a process known ...

  8. Mass in special relativity - Wikipedia

    en.wikipedia.org/wiki/Mass_in_special_relativity

    The relativistic mass is the sum total quantity of energy in a body or system (divided by c2). Thus, the mass in the formula is the relativistic mass. For a particle of non-zero rest mass m moving at a speed relative to the observer, one finds. In the center of momentum frame, and the relativistic mass equals the rest mass.

  9. Electromagnetic wave equation - Wikipedia

    en.wikipedia.org/wiki/Electromagnetic_wave_equation

    The electromagnetic wave equation is a second-order partial differential equation that describes the propagation of electromagnetic waves through a medium or in a vacuum. It is a three-dimensional form of the wave equation. The homogeneous form of the equation, written in terms of either the electric field E or the magnetic field B, takes the form: