How much power is radiated by the human body?

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SUMMARY

The power radiated by the human body can be calculated using the Stefan-Boltzmann law, represented by the equation P/A = σT4, where σ = 5.67 × 10−8 W m−2 K−4. For a blackbody cylinder with a height of 1.22 m and a radius of 0.15 m at human body temperature, the total power radiated is significantly higher than that of a human body due to the skin's inefficiency as a radiator in the infrared spectrum. Participants are encouraged to show their attempted solutions in accordance with forum policies for homework assistance.

PREREQUISITES
  • Understanding of the Stefan-Boltzmann law
  • Knowledge of blackbody radiation concepts
  • Familiarity with basic thermodynamic principles
  • Ability to perform calculations involving surface area and temperature in Kelvin
NEXT STEPS
  • Research the implications of skin emissivity on thermal radiation
  • Learn about the calculation of surface area for cylindrical objects
  • Explore the differences between ideal blackbody and real-world radiators
  • Study the effects of temperature on radiation power output
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Physicists, engineering students, and anyone interested in thermodynamics and heat transfer principles will benefit from this discussion.

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The power per unit area radiated by an ideal blackbody radiator is P/A = σT4, where P = power, A = surface area, the Stefan-Boltzmann constant is σ = 5.67 ×10−8 W m−2 K−4, and T = temperature (in the absolute kelvin scale).

How much power is radiated by the human body? Calculate the total power radiated by a blackbody cylinder of height 1.22 m and radius 0.15 m at human body temperature. (Ignore radiation from the ends of the cylinder.) (The result is considerably more than the power radiated by a human body, because skin is not a good radiator in the infrared.)
 
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