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PRACTICE / Thermal radiation

Emission is not net cooling

A surface emits 10 W when at 300 K. Its area and emissivity remain fixed. It is heated to 600 K inside a large isothermal enclosure at 300 K.

Find its net radiative power loss.

Organize the givens & assumptions
  • Emitted power at 300 K: 10 W
  • Heated surface: 600 K
  • Enclosure: 300 K
  • Fixed area and emissivity

Diffuse grey surface exchanging radiation only with the enclosure; absorptivity equals emissivity and is temperature independent. Ignore conduction and convection.

  1. A10 W10\ \mathrm W
  2. B80 W80\ \mathrm W
  3. C150 W150\ \mathrm W
  4. D160 W160\ \mathrm W

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