FUNDAMENTALS OF PHYSICS (LLF)+WILEYPLUS
11th Edition
ISBN: 9781119459132
Author: Halliday
Publisher: WILEY
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Chapter 44, Problem 42P
Due to the presence everywhere of the cosmic background
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Due to the presence everywhere of the cosmic background radiation, the minimum possible temperature of a gas in interstellar or intergalactic space is not 0 K but 2.7 K. This implies that a significant fraction of the molecules in space that can be in a lowlevel excited state may, in fact, be so. Subsequent de-excitation would lead to the emission of radiation that could be detected. Consider a (hypothetical) molecule with just one possible excited state. (a) What would the excitation energy have to be for 25% of the molecules to be in the excited state? (b) What would be the wavelength of the photon emitted in a transition back to the ground state?
The partition function of an ensemble at a temperature T is
N
Z = (2 cosh
kgT
where kg is the Boltzmann constant. The heat capacity of this ensemble at T = is
X Nkg, where the value of X is
%3D
kB
(up to two decimal places).
1 (a) Show that the entropy per photon in blackbody radiation is independent of the
temperature, and in d spatial dimensions is given by
En-d-1
s = (d + 1)
n=1
E n-d
n=1
(b) Show that the answer would have been d + 1 if the photons obeyed Boltzman
statistics.
Chapter 44 Solutions
FUNDAMENTALS OF PHYSICS (LLF)+WILEYPLUS
Ch. 44 - Prob. 1QCh. 44 - Prob. 2QCh. 44 - Prob. 3QCh. 44 - Prob. 4QCh. 44 - Prob. 5QCh. 44 - Prob. 6QCh. 44 - Prob. 7QCh. 44 - Prob. 8QCh. 44 - Prob. 9QCh. 44 - Prob. 10Q
Ch. 44 - Prob. 11QCh. 44 - Prob. 1PCh. 44 - Prob. 2PCh. 44 - Prob. 3PCh. 44 - Prob. 4PCh. 44 - Prob. 5PCh. 44 - Prob. 6PCh. 44 - Prob. 7PCh. 44 - GO A positive tau , rest energy = 1777 MeV is...Ch. 44 - Prob. 9PCh. 44 - Prob. 10PCh. 44 - Prob. 11PCh. 44 - Prob. 12PCh. 44 - Prob. 13PCh. 44 - Prob. 14PCh. 44 - Prob. 15PCh. 44 - Prob. 16PCh. 44 - Prob. 17PCh. 44 - Prob. 18PCh. 44 - Prob. 20PCh. 44 - Prob. 21PCh. 44 - Prob. 22PCh. 44 - Prob. 23PCh. 44 - Prob. 24PCh. 44 - Prob. 25PCh. 44 - Prob. 26PCh. 44 - Prob. 27PCh. 44 - Prob. 28PCh. 44 - Prob. 29PCh. 44 - Prob. 30PCh. 44 - Prob. 31PCh. 44 - Prob. 32PCh. 44 - Prob. 33PCh. 44 - Prob. 34PCh. 44 - Prob. 35PCh. 44 - What would the mass of the Sun have to be if Pluto...Ch. 44 - Prob. 37PCh. 44 - Use Wiens law see Problem 37 to answer the...Ch. 44 - Prob. 39PCh. 44 - Prob. 40PCh. 44 - Prob. 41PCh. 44 - Due to the presence everywhere of the cosmic...Ch. 44 - SSM Suppose that the radius of the Sun were...Ch. 44 - Prob. 44PCh. 44 - Prob. 45PCh. 44 - Prob. 46PCh. 44 - Prob. 47PCh. 44 - Prob. 48PCh. 44 - Prob. 49PCh. 44 - Prob. 50PCh. 44 - Prob. 51PCh. 44 - Prob. 52PCh. 44 - Prob. 53PCh. 44 - Prob. 54P
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