Physics for Scientists and Engineers with Modern Physics
10th Edition
ISBN: 9781337553292
Author: Raymond A. Serway, John W. Jewett
Publisher: Cengage Learning
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Chapter 44, Problem 44AP
To determine
The order of magnitude of the threshold temperature.
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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.
If the electrons gain this energy by collision
between hydrogen atoms in a high temperature
gas, find the minimum temperature of the heated
hydrogen gas. The thermal energy of the heated
atoms is given by 3 kB T 2, where the Boltzmann
constant is 1.38 × 10-23 J/K. Answer in units of K.
The radio galaxy Cygnus A possesses a lobe of plasma that is detected by both radio
and X-ray observatories. The temperature of the X-ray-emitting plasma is 4 keV and the
number density of the particles in the plasma is 4x10 m-3. Assume that the plasma is
composed solely of completely ionized hydrogen, so the number densities of protons and
electrons per cubic meter are identical.
* the given number density of particles corresponds to the number density of hydrogen nuclei, so you
can safely assume that the number density of electrons is equivalent to this number density
a) Compute the time in seconds between collisions between electrons and ions in the plasma.
b) Compute the ratio of the time in seconds between collisions to the age of the Universe (13.7
billion years, where 1 year = 3.15x107 s). Therefore, how many collisions has a typical elec-
tron experienced with a proton in this plasma during the lifetime of the Universe?
c) Compute the mean free path in meters traveled by the…
Chapter 44 Solutions
Physics for Scientists and Engineers with Modern Physics
Ch. 44.2 - Prob. 44.1QQCh. 44.5 - Prob. 44.3QQCh. 44.5 - Prob. 44.4QQCh. 44.8 - Prob. 44.5QQCh. 44.8 - Prob. 44.6QQCh. 44 - Prob. 1PCh. 44 - Prob. 2PCh. 44 - Prob. 3PCh. 44 - Prob. 4PCh. 44 - Prob. 5P
Ch. 44 - Prob. 6PCh. 44 - Prob. 7PCh. 44 - Prob. 8PCh. 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. 29PCh. 44 - Prob. 30PCh. 44 - The various spectral lines observed in the light...Ch. 44 - Prob. 33PCh. 44 - Prob. 34APCh. 44 - Prob. 35APCh. 44 - Prob. 36APCh. 44 - Prob. 37APCh. 44 - Prob. 38APCh. 44 - Prob. 39APCh. 44 - Prob. 40APCh. 44 - An unstable particle, initially at rest, decays...Ch. 44 - Prob. 42APCh. 44 - Prob. 43APCh. 44 - Prob. 44APCh. 44 - Prob. 45APCh. 44 - Prob. 46CPCh. 44 - Prob. 47CPCh. 44 - Prob. 48CPCh. 44 - Prob. 49CP
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