The relationship between absorbtion, emissivity and reflection

The emissivity of a surface is equal to its absorption coefficient, and when combined with reflectivity and transmissibility, it equals 1. There is a distinction between initial transmissibility and absorption, as the latter occurs when radiation enters the body of the material. These two forms of absorption are related in terms of energy conservation.In summary, the conversation discusses the absorption coefficient of a material surface and its connection to its emissivity, reflecting the conservation of energy. The equation for this includes the emissivity, reflectivity, and transmissibility, where the latter can be divided into initial transmissibility and absorption within the material. These two forms of absorption are related in terms of energy conservation.
  • #1
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 absorbtion, which is termed attenuation, in which the transmitted radiation is slowly absorbed as it goes through the body. How are these 2 forms of absorbtion related?
 
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  • #2
That is a general statement, and a consequence of conservation of energy.
 

What is the relationship between absorption, emissivity, and reflection?

The relationship between absorption, emissivity, and reflection is known as the energy balance. These three factors are all related to the amount of energy that is absorbed and emitted by a material. The amount of energy that is absorbed by a material is equal to the amount of energy that is emitted, minus the amount that is reflected.

How does the color of a material affect its absorption, emissivity, and reflection?

The color of a material can affect its absorption, emissivity, and reflection. Darker colors tend to have higher absorption rates, as they absorb more light energy. Lighter colors tend to have higher reflectivity, as they reflect more light energy. Emissivity, on the other hand, is not affected by color.

Can the absorption, emissivity, and reflection of a material be changed?

Yes, the absorption, emissivity, and reflection of a material can be changed. This can be done by altering the properties of the material, such as its color or surface texture. For example, a material with a rougher surface may have higher emissivity and lower reflectivity compared to a material with a smooth surface.

What factors can influence the absorption, emissivity, and reflection of a material?

Several factors can influence the absorption, emissivity, and reflection of a material, including its composition, color, surface texture, and temperature. The type and wavelength of the energy being absorbed can also play a role in these factors. Environmental conditions, such as humidity and air pressure, can also impact these properties.

Why is understanding the relationship between absorption, emissivity, and reflection important for scientists?

Understanding the relationship between absorption, emissivity, and reflection is important for scientists because it allows them to accurately measure and predict the energy balance of materials. This knowledge is crucial in various fields, such as material science, thermodynamics, and climate research. It also helps in the development of more efficient and sustainable technologies.

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