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About this exercise type...The change of the intensity caused by absorption during the passage of radiation through a volume of gas is proportional to
| — | the temperature of the gas; |
| — | the absorption cross-section of the gas; |
| — | the density of the absorber; |
| — | the wavelength of the radiation; |
| — | the length of the optical path. |
The product of the density of the absorber and the absorption cross-section gives
| — | the opacity; |
| — | the absorption coefficient; |
| — | the transmissivity. |
The opacity of a volume of gas is also known as
| — | the optical length; |
| — | the optical density; |
| — | the optical depth; |
| — | the absorptivity. |
The opacity of a volume of gas is
| — | the product of the absorption coefficient and the length of the optical path; |
| — | the product of the absorption cross-section, the density of the absorber and the length of the optical path; |
| — | the density of the absorber; |
| — | the absorption component in the Beer-Lambert equation; |
| — | the absorptivity for a specified wavelength. |
Transmissivity is
| — | the inverse of the optical depth; |
| — | the ratio of the absorbed intensity over the initial intensity; |
| — | the inverse of the the absorption cross-section; |
| — | the negative exponent of the opacity. |
Absorptivity is
| — | the transmissivity minus one; |
| — | one minus the opacity; |
| — | one minus the transmissivity; |
| — | one minus the absorption cross-section. |
The 'optically thick case' occurs when
| — | the density of the absorber is very low; |
| — | the opacity approaches infinity; |
| — | the absorptivity approaches 1. |
The following are functions of the wavelength of the transmitted radiation
| — | the length of the optical path; |
| — | the absorption cross-section; |
| — | the opacity; |
| — | the density of the absorber; |
| — | the tranmissivity; |
| — | the absoptivity. |
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