Question

For photons in equilibrium at temperature Tin a cavity of volume V, Eq. (7.20) gives the number of photons with circular frequency in the range ω to ω + do. 3. (a) Show that the total number of photons in equilibrium at temperature T in a cavity of volume Vis 2.40V kT ће Cite any reference you use to evaluate the integral. Credit will be given for evaluating it yourself. Hint: You might make use of the Riemann zeta functions (Table 7.1 lecture notes)] [8 marks] (b) The cosmic ray background radiation in the Universe has a temperature-3 K. How many photons per cm' does it contain? xxarkl (c) Show that the entropy per photon is 3.602k [I mark] (d) Show that the entropy of the cosmic background radiation is the same anywhere in the Universe [Hint: From the internet or a textbook, find the expressions that relate the comoving volume of the Universe and the temperature of the cosmic background radiation both as a function of redshift z.] 2 marks]

Answer 1

2 전 예쁜1-1 KT 2 21 3

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