p14qz8 - photon that this excited electron can emit c What...

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Physics 14 - Quiz 8 - Winter 2009 SHOW ALL YOUR WORK AND REASONING 1. (2 pts) A friend gives you a radioactive isotope in a box and asks you to open it in 16 hours. The isotope has a half-life of 4 hours. When you open the box and analyze the sample, there is just 25 grams of the radioactive isotope left. What was the original mass of the isotope? 2. (1 pt) What really happens when beta decay occurs? 3. (3 pts) The energy levels of an atom are shown below. The ground state of the atom (E 1 ) is shown. An electron is in the second excited state, with energy E 3 = 10.0 eV. a) How could the electron have gotten to this state? b) What is the energy of the highest frequency
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Unformatted text preview: photon that this excited electron can emit? c) What is the energy of the lowest frequency photon that this excited electron can emit? 4. (2 pts) Why can intense red light not cause electrons to be emitted from a metal surface but weak ultraviolet light can? 5. (2 pts) An isotope of Astatine ( 218 85 At ) decays first by alpha decay, then beta decay. What is the final isotope? (Some possibly important information about the atomic numbers of some elements: 81 Tl , 82 Pb , 83 Bi , 84 Po , 85 At , 86 Rn , 87 Fr , 88 Ra.) E 4 = 12.0 eV E 3 = 10.0 eV E 2 = 6.0 eV E 1 = 1.0 eV electron (ground state)...
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This note was uploaded on 02/10/2011 for the course PHYS 14 taught by Professor Physcs14 during the Spring '09 term at Santa Monica.

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