Unformatted text preview: Homework (2) for Physics 316, Modern Physics I (Hoffstaetter/Drasco/Thibault) Due Date: Friday, 02/11/04  9:05 in 132 Rockefeller Hall Exercise 1: a) Given the knowledge that atomic diameters are of the order of 1 or 2 ˚ A , estimate the order of magnitude of the number of atoms in a human being and in the whole earth (use 40000km as circumference). b) (Bonus) Assume that all molecules of Plato’s last breath are still in the atmosphere, how many of them are on average contained in every breath you take? For a rough approximation, assume that the atmosphere is 5km thick, that the mol volume is 22.4L/mol in all of the atmosphere, and that a typical breath contains about 1L. Exercise 2: Assume the Hydrogen atom consists of a sphere with radius R and with a uniform positive charge density in which a negatively charged electron moves freely. a) Show that the electron experiences a force C~ r toward the center of the sphere and show that the orbits of the electron in such an atom would be ellipses. It is easiest to work in Cartesianthe orbits of the electron in such an atom would be ellipses....
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 Spring '05
 HOFFSTAETTER
 Physics, Atom, Work, Fundamental physics concepts, negatively charged electron, positive charge density

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