The relationship between absorbtion, emissivity and reflection

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SUMMARY

The discussion centers on the relationship between absorption, emissivity, and reflection, specifically referencing Kirchhoff's law of thermal radiation. It establishes that the absorption coefficient of a material's surface equals its emissivity, leading to the equation: emissivity + reflectivity + transmissibility = 1. This relationship applies to thermal radiation and highlights the concept of attenuation, where transmitted radiation is absorbed as it penetrates the material. The conversation emphasizes the conservation of energy in these processes.

PREREQUISITES
  • Understanding of Kirchhoff's law of thermal radiation
  • Familiarity with the concepts of emissivity and reflectivity
  • Knowledge of radiation transmissibility
  • Basic principles of energy conservation in physics
NEXT STEPS
  • Research the implications of Kirchhoff's law in different materials
  • Explore the concept of attenuation in various media
  • Study the mathematical modeling of emissivity and reflectivity
  • Investigate applications of thermal radiation in engineering
USEFUL FOR

Physicists, materials scientists, and engineers interested in thermal radiation properties and energy conservation principles.

swampwiz
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As I understand it, the absorption coefficient of a surface of material is the same as its emissivity (due to Kirchoff's law of thermal radiation), and that the net of this and the tranmissibility is

emissivity + reflectivity + transmissibility = 1

Is this a general statement about any radiation, or only about thermal "black-body" radiation?

I presume that the tranmissibility is the initial transmissibility of the surface, since once inside the body of the material, there is absorption, which is termed attenuation, in which the transmitted radiation is slowly absorbed as it goes through the body. How are these 2 forms of absorption related?
 
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That is a general statement, and a consequence of conservation of energy.
 

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