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Midterm 1

# Midterm 1 - PHYS 320 Spring 2007 Midterm Test 4:00 pm...

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PHYS 320 Spring 2007 Midterm Test 3/5/07 @ 4:00 pm 1 SOLUTIONS 1. Complete the table below by entering the particles (photon, electron, or N/A) that initiate and result from the processes listed, indicate if the process is elastic, inelastic, or not applicable. Give a brief description of Photoelectric effect Experiment In Out Type of scattering Compton Scattering photon Photon + e - Inelastic Electron diffraction electron electron Elastic Photoelectric effect photon electron Inelastic. Blackbody radiation N/A photon N/A Visible light interference photon photon Elastic Photoelectric effect: Photons hit a target and eject electrons. Energy of a photon is transmitted to an electron. Part of this energy is spent to overcome the barrier (metal work function) and the rest is kinetic energy of the ejected electron: E photon = E K + φ 2. A positron with kinetic energy E K = 10 MeV hits an electron at rest (E K = 0). As a result of their annihilation, two identical photons are created and fly apart (hint: total energy is conserved). Find a) velocity of the positron before collision , b) energy and wavelength of the photons. 2 2 e+ 2 2 10 0.511 10.511 MeV 0 0.511 0.511 MeV 10.511 0.511 11.022 MeV 10.511 20.57 0.511 1 1 0.9988 0.9988 11.022 MeV 5.511 MeV 22 eK e e tot e e e e e e e tot photon p EE m c m c EEE E mc u uc c E E γ λ + +− + + + + =+ = + = = + = =+= + = == = =− = = = 4 6 1240 eV nm 2.25 10 nm 5.511 10 eV hoton photon hc E = × ×

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PHYS 320 Spring 2007 Midterm Test 3/5/07 @ 4:00 pm 2 3. Find the energy and wavelength of the L α x-ray line for cobalt (Co).
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Midterm 1 - PHYS 320 Spring 2007 Midterm Test 4:00 pm...

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