Show for a photon gas that: (a) (b) d j /dV = j /3V (c) p

Show for a photon gas that:

(a)

(b) dω_j/dV = –ω_j/3V 

(c) p = U/3V

Thus the radiation pressure is equal to 1/3 × (energy density).

(d) Compare the pressure of thermal radiation with the kinetic pressure of a gas of H atoms at a concentration of 1 mole cm^-3 characteristic of the Sun. at what temperature (roughly) are the two pressures equal? The average temperature of the sun is believed to be near 100 mole cm^-3at the center, where the kinetic pressure is considerably higher than the radiation pressure.

Transcribed Image Text:

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