Entropy Change from Sun to Earth: 1000 J Radiation Transfer Calculation

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SUMMARY

The entropy change when 1,000 J of energy is transferred by radiation from the Sun (5,700 K) to the Earth (290 K) is positive, contrary to initial assumptions of a negative change. The discussion clarifies that while the Earth is cooler, the process is irreversible, leading to an overall increase in entropy. This aligns with the second law of thermodynamics, which states that the total entropy of an isolated system can never decrease.

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  • Knowledge of temperature scales and their implications on energy transfer
  • Basic principles of radiation and energy transfer
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Homework Statement


The temperature at the surface of the Sun is approximately
5 700 K, and the temperature at the surface of the
Earth is approximately 290 K. What entropy change
occurs when 1 000 J of energy is transferred by radiation
from the Sun to the Earth?


Homework Equations





The Attempt at a Solution


So I know how to solve this problem. My question is more about the sign than about the calculation.
I left my answer of ΔS as negative, but the book lists it as positive. It seems to me like the change should be negative because the T is cooler on Earth hence entropy should decrease within this closed system.
 
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Ah of course that makes sense! Since this is an irreversible process the entropy must increase.
Thank you!
 

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