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  2. Radiation pressure - Wikipedia

    en.wikipedia.org/wiki/Radiation_pressure

    Solar radiation pressure strongly affects comet tails. Solar heating causes gases to be released from the comet nucleus, which also carry away dust grains. Radiation pressure and solar wind then drive the dust and gases away from the Sun's direction. The gases form a generally straight tail, while slower moving dust particles create a broader ...

  3. Stefan–Boltzmann law - Wikipedia

    en.wikipedia.org/wiki/Stefan–Boltzmann_law

    [3]: 66n, 541 (This is a trivial conclusion, since the emissivity, , is defined to be the quantity that makes this equation valid. What is non-trivial is the proposition that ε ≤ 1 {\displaystyle \varepsilon \leq 1} , which is a consequence of Kirchhoff's law of thermal radiation .

  4. Poynting vector - Wikipedia

    en.wikipedia.org/wiki/Poynting_vector

    The results can then be applied more generally, for instance, by representing incoherent radiation as a superposition of such waves at different frequencies and with fluctuating amplitudes. We would thus not be considering the instantaneous E ( t ) and H ( t ) used above, but rather a complex (vector) amplitude for each which describes a ...

  5. Poynting–Robertson effect - Wikipedia

    en.wikipedia.org/wiki/Poynting–Robertson_effect

    Radiation pressure affects the effective force of gravity on the particle: it is felt more strongly by smaller particles, and blows very small particles away from the Sun. It is characterized by the dimensionless dust parameter β {\displaystyle \beta } , the ratio of the force due to radiation pressure to the force of gravity on the particle:

  6. List of physical quantities - Wikipedia

    en.wikipedia.org/wiki/List_of_physical_quantities

    Pressure gradient: Pressure per unit distance pascal/m L −2 M 1 T −2: vector Temperature gradient: steepest rate of temperature change at a particular location K/m L −1 Θ: vector Torque: τ: Product of a force and the perpendicular distance of the force from the point about which it is exerted

  7. Photon gas - Wikipedia

    en.wikipedia.org/wiki/Photon_gas

    In low-dimensional systems, for example in dye-solution filled optical microcavities with a distance between the resonator mirrors in the wavelength range where the situation becomes two-dimensional, also photon gases with tunable chemical potential can be realized. Such a photon gas in many respects behaves like a gas of material particles.

  8. Boltzmann equation - Wikipedia

    en.wikipedia.org/wiki/Boltzmann_equation

    The equation is a nonlinear integro-differential equation, and the unknown function in the equation is a probability density function in six-dimensional space of a particle position and momentum. The problem of existence and uniqueness of solutions is still not fully resolved, but some recent results are quite promising.

  9. Radiation stress - Wikipedia

    en.wikipedia.org/wiki/Radiation_stress

    The radiation stress – mean excess momentum-flux due to the presence of the waves – plays an important role in the explanation and modeling of various coastal processes: [1] [2] [3] Wave setup and setdown – the radiation stress consists in part of a radiation pressure, exerted at the free surface elevation of the mean flow