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  2. Black-body radiation - Wikipedia

    en.wikipedia.org/wiki/Black-body_radiation

    For a black body (a perfect absorber) there is no reflected radiation, and so the spectral radiance is entirely due to emission. In addition, a black body is a diffuse emitter (its emission is independent of direction). Blackbody radiation becomes a visible glow of light if the temperature of the object is high enough. [19]

  3. Kirchhoff's law of thermal radiation - Wikipedia

    en.wikipedia.org/wiki/Kirchhoff's_law_of_thermal...

    A body at temperature T radiates electromagnetic energy. A perfect black body in thermodynamic equilibrium absorbs all light that strikes it, and radiates energy according to a unique law of radiative emissive power for temperature T (Stefan–Boltzmann law), universal for all perfect black bodies. Kirchhoff's law states that:

  4. Stefan–Boltzmann law - Wikipedia

    en.wikipedia.org/wiki/Stefan–Boltzmann_law

    A so-called grey body is a body for which the spectral emissivity is independent of wavelength, so that the total emissivity, , is a constant. [ 3 ] : 71 In the more general (and realistic) case, the spectral emissivity depends on wavelength.

  5. Emissivity - Wikipedia

    en.wikipedia.org/wiki/Emissivity

    Emissivity of a body at a given temperature is the ratio of the total emissive power of a body to the total emissive power of a perfectly black body at that temperature. Following Planck's law , the total energy radiated increases with temperature while the peak of the emission spectrum shifts to shorter wavelengths.

  6. Better Business Bureau (BBB) complaints and accreditation ...

    www.aol.com/lifestyle/better-business-bureau-bbb...

    With a legacy of more than 100 years, the Better Business Bureau (BBB) is the go-to watchdog for evaluating businesses and charities. The nonprofit organization maintains a massive database of ...

  7. Black body - Wikipedia

    en.wikipedia.org/wiki/Black_body

    A black body or blackbody is an idealized physical body that absorbs all incident electromagnetic radiation, regardless of frequency or angle of incidence. The radiation emitted by a black body in thermal equilibrium with its environment is called black-body radiation. The name "black body" is given because it absorbs all colors of light.

  8. Low emissivity - Wikipedia

    en.wikipedia.org/wiki/Low_emissivity

    Emissivity is the value given to materials based on the ratio of heat emitted compared to a perfect black body, on a scale from zero to one. A black body would have an emissivity of 1 and a perfect reflector would have a value of 0. Kirchhoff's law of thermal radiation states that absorption equals emissivity opaque (ε opaque) for every ...

  9. Planck's law - Wikipedia

    en.wikipedia.org/wiki/Planck's_law

    The table on the right shows how the radiation of a black body at this temperature is partitioned, and also how sunlight is partitioned for comparison. Also for comparison a planet modeled as a black body is shown, radiating at a nominal 288 K (15 °C) as a representative value of the Earth's highly variable temperature.