Department of Physics
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the picture from the trip
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American Institute of Physics
Homework #6: Do not turn these in since there is a test this Friday, March 7.
That's all for homework #6.
- problem 4.22
- The quantity 'kT' is a powerful thing that allows you to make fairly intelligent estimates of the available thermal energy involved in many situations. Getting a feel for the amounts of these energies at various temperatures will make your life in physics easier. Calculate the following:
(a) The temperature (in Kelvin, of course) that corresponds to 1.0eV of energy. Recall that kBoltzmann=8.6174x10-5 eV/K.
(b) The energy in units of eV associated with room temperature of 295K.
(c) The energy in units of eV at the surface of the sun (5,800K).
(d) The temperature required to ionize a hydrogen atom in its ground state with n=1 (recall En=(-)13.6eV Z2/n2 where Z=atomic number).
- Consider a conductor made of 82Pb (lead). Assume 82Pb has a band gap energy 0.83eV. Calculate the following:
(a) The number density of electrons in the ground state in this conductor. Note that 82Pb has 4 valence electrons. And recall that http://webelements.com/ is a useful site.
(b) The number density of electrons in the conducting band of 82Pb at 1,500K, 1,200K, 525K, 350K, and 273K.