Review. The energy required to excite an atom is on the
Chapter 46, Problem 63(choose chapter or problem)
Review. The energy required to excite an atom is on the order of 1 eV. As the temperature of the Universe dropped below a threshold, neutral atoms could form from plasma and the Universe became transparent. Use the Boltzmann distribution function e 2E/kBT 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
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