Fundamentals of Physics Extended
10th Edition
ISBN: 9781118230725
Author: David Halliday, Robert Resnick, Jearl Walker
Publisher: Wiley, John & Sons, Incorporated
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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?
You are performing work as an assistant to a cosmology professor. She asks you to estimate the temperature of the Universe at a time after the Big Bang when neutral atoms could form from the plasma and the Universe became transparent. She tells you that the energy required to excite an atom is on the order of 1 eV. She suggests you use the Boltzmann distribution function e-E/k BT to find the order of magnitude of the threshold temperature at which 1.00% of a population of photons has energy greater than 1.00 eV.
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).
Chapter 44 Solutions
Fundamentals of Physics Extended
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 - a A stationary particle 1 decays into parties 2...Ch. 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. 19PCh. 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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