Stefan's Law And Definition Of Temperature

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SUMMARY

The discussion centers on Stefan's Law, expressed as I = σ T^4, which accurately describes the relationship between intensity and temperature for blackbodies. However, it is not utilized as a standard definition of temperature at specific points, such as 100°C, due to the challenges of emissivity variability, the complexity of tracking total radiation across all wavelengths, and the cumbersome nature of calculations involved. The consensus is that Stefan's Law does not enhance the understanding of temperature or the energy exchange between objects.

PREREQUISITES
  • Understanding of Stefan-Boltzmann Law
  • Knowledge of blackbody radiation principles
  • Familiarity with emissivity and its impact on thermal radiation
  • Basic concepts of thermodynamics and heat transfer
NEXT STEPS
  • Research the implications of emissivity on thermal measurements
  • Explore the concept of blackbody radiation in detail
  • Study the methods for tracking radiation across different wavelengths
  • Investigate alternative definitions of temperature in thermodynamics
USEFUL FOR

Physicists, engineers, and students studying thermodynamics, particularly those interested in thermal radiation and temperature measurement techniques.

neelakash
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The relation I= \sigma \ T^4 is exact for blackbodies and holds for all temperatures.Why is this relation not used as a basis of a definition of temperature at,say, 100*C?

(i)We do not deal with all black bodies around us.So, for specific objects,we are to put the value of emissivity which is unknown to us.

(ii) T will be a very slowly varying function of Intensity I.The temperature difference of two bodies will be very difficult to find if the total radiation is not tracked.This means,you have to keep track of all the wavelengths...

(iii)The calculation will be cumbersome...
 
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i am not sure if this is the reason but the reason i think stefan's law is not used to define temperature is because it doesn't actually help us understand anything about temperature and also the energy given out by an object in the surrounding due to the difference of temperature depends on the temperature of the body to which it is giving the heat to...
 

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