Understanding Black Body Radiation and the Sun's Color Temperature

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SUMMARY

The discussion clarifies the relationship between temperature and color in black body radiation, specifically addressing the Sun's color temperature and the color of flames. It establishes that the Sun emits light with a peak frequency in the yellow region due to its temperature, while blue flames, such as those from a Bunsen burner, are not true black body radiators. Instead, the color of flames is influenced by the chemical reactions of the fuel being burned. Black body radiators, like stars, exhibit a shift to bluer light as their temperature increases.

PREREQUISITES
  • Understanding of black body radiation principles
  • Knowledge of color temperature and its measurement in Kelvin
  • Familiarity with the concept of spectral emissions from different materials
  • Basic chemistry knowledge regarding combustion and flame color
NEXT STEPS
  • Research the Planck's Law of black body radiation
  • Explore the concept of Wien's Displacement Law
  • Study the spectral classification of stars, focusing on B-type stars
  • Investigate the chemistry of combustion and how it affects flame color
USEFUL FOR

Students of physics, chemists, educators, and anyone interested in the principles of thermodynamics and light emission.

riz
So, if frequency(max) of light emitted from an object proportional to temperature in kelvin, how can sun have max frequency around the yellow region while blue flames are much less hot?
 
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Do you mean blue flame like that produced by a Bunsen burner (or a gas stove)?
The reason is that flames in general are not black body radiators. The colour of a flame is determined by the type of chemical reactions occurring when the given type of fuel is burning.

Conversely, radiators which can be approximated as black bodies, e.g. stars, or hot pieces of metal, get bluer with higher temperature.
(0, B stars are blue, e.g. Rigel)
 
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riz said:
So, if frequency(max) of light emitted from an object proportional to temperature in kelvin, how can sun have max frequency around the yellow region while blue flames are much less hot?
From Wikipedia:

Bunsen burner:
1024px-Spectrum_of_blue_flame_-_intensity_corrected.png


Black bodies:

600px-Black_body.svg.png
 

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