Assignment_12 08 - Physics 214 Assignment 12(complete Concepts Compton scattering DeBroglie wavelength of particles Electron diffraction Wave

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Physics 214 Assignment 12 (complete) Concepts: Compton scattering Schrodinger equation DeBroglie wavelength of particles Electron diffraction Wave functions and interpretation Free particles Particle in a box Reading: Y&F, Vol. 3, Chapters 38, 39 and 40 Assignment: Due Thursday, April 24. Please turn in this sheet stapled to the top of your work. Physics Problems: 1. Y&F, Chapter 38, Problem 38.75 2. There have been many claims that electromagnetic radiation from power lines, cell phones and microwave ovens cause cancer. Is this possible? In general, radiation causes cancer by breaking chemical bonds, especially in DNA, eventually leading to uncontrolled cell proliferation. Let's compare the energies of photons with important energies in the cell. (a) As in the photoelectric effect, where the kinetic energy of the ejected electrons depends only on the wavelength of light/ photon energy and not on light intensity, the breaking of bonds is only determined by photon frequency. The most important bonds in biological materials are the C-C and C-H bonds. The bond energy between two carbon atoms varies from ~1 eV to 5.2 eV, depending upon what other atoms are bonded to the carbons. Similarly, the bond energy between a hydrogen atom and a carbon atom varies from 3.6 eV to 5.7 eV. C-N and C-O bond energies are around 1.5 eV. Taking a lower bound of 1 eV, what is the ratio of the bond energy to the photon energy for the photons emitted by (i) power lines, (ii) cell phones and (iii) microwave ovens? (b) The other important energy scale is that of thermal vibrations and translations of the molecules. This scale is ~ k B T, where k B = 1.38 x 10 -23 m 2 kg s -2 K -1 and T is the temperature in Kelvin. At room temperature, k B T~26 meV. How does this compare with the energy of power line, cell phone and microwave photons? (Incidentally, if photons of this energy were hazardous to your health, you would have died long ago. You've got huge numbers of them bouncing around inside your body right now. k B T is near the peak frequency x h of the blackbody radiation that pervades all objects at finite temperature.) (c) From your answer to Problem 9(c) on Assignment 11, what frequencies / wavelengths of EM waves would you expect to be hazardous to your bonds?
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This note was uploaded on 03/31/2009 for the course PHYS 214 taught by Professor Thorne during the Spring '08 term at Cornell University (Engineering School).

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Assignment_12 08 - Physics 214 Assignment 12(complete Concepts Compton scattering DeBroglie wavelength of particles Electron diffraction Wave

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