Entropy Change in Blackbody Radiation System in Thermal Equilibrium

In summary, the conversation discusses an evacuated container with volume V and temperature T that contains black body radiation with an energy density of 4T4/c. The container is in thermal contact with a heat bath at temperature Tr and the heat capacity of the container material is neglected. It is shown that the overall change in entropy of the universe after reaching thermal equilibrium is given by Stot=(4VTr3/3c)(1-t3(4-3t)), where t=T/Tr. The speaker is having difficulty understanding the equation and asks for help.
  • #1
blueyellow
An evacuated container with volume V and at a temperature T contains black body radiation with an energy density equal to 4T4/c


S(T,V)=16VT3/3c

The container is placed in thermal contact with a heat bath at temperature Tr. If the heat capacity of the cavity material itself is negligible, show that the overall change in entropy of the universe after the system and heat bath have reached thermal equilibrium is

Stot=(4VTr3/3c)(1-t3(4-3t))

t= T/Tr

i am so stuck. please help.i have tried expanding it out to see whether it looks like anything familiar, but no
 
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  • #2
r u from ucl??
 

1. What is blackbody radiation entropy?

Blackbody radiation entropy refers to the measure of disorder or randomness in the distribution of electromagnetic radiation emitted by a blackbody. It is a fundamental concept in thermodynamics and statistical mechanics.

2. How is blackbody radiation entropy related to temperature?

The blackbody radiation entropy is directly proportional to the temperature of the blackbody. As the temperature increases, the amount of energy and radiation emitted by the blackbody also increases, resulting in a higher level of disorder and entropy.

3. Why is blackbody radiation entropy important?

Blackbody radiation entropy plays a crucial role in understanding the behavior of thermal systems and their equilibrium states. It is also a key concept in the development of the laws of thermodynamics and the study of heat transfer.

4. How is blackbody radiation entropy calculated?

The blackbody radiation entropy can be calculated using the formula S = kBln(W), where S is the entropy, kB is the Boltzmann constant, and W is the number of microstates or possible arrangements of energy in the system.

5. Can the blackbody radiation entropy be decreased?

No, the blackbody radiation entropy can only increase or stay constant. According to the second law of thermodynamics, the total entropy of an isolated system always increases over time and never decreases.

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