HW13-solutions

# HW13-solutions - gilbert (amg3448) – HW13 – tsoi –...

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Unformatted text preview: gilbert (amg3448) – HW13 – tsoi – (57210) 1 This print-out should have 16 questions. Multiple-choice questions may continue on the next column or page – find all choices before answering. 001 (part 1 of 2) 10.0 points A hypothetical atom has four energy states as shown.- 1- 2- 3- 4- 5- 6- 7- 8 n = 4 n = 3 n = 2 n = 1 Energy(eV) Which of the following photon energies E ν could NOT be found in the emission spectra of this atom after it has been excited to the n = 4 state? 1. E ν = 2 eV 2. E ν = 3 eV 3. E ν = 5 eV 4. E ν = 1 eV 5. E ν = 4 eV correct Explanation: By subtraction, the transition from n = 4 to n = 3 would release 1 eV; from n = 4 to n = 2 would release 3 eV; from n = 3 to n = 2 would release 2 eV; from n = 3 to n = 1 would release 5 eV. The only choice remaining is 4 eV . 002 (part 2 of 2) 10.0 points Which of the following transitions will pro- duce the photon with the longest wavelength? 1. n = 3 to n = 2 2. n = 4 to n = 3 correct 3. n = 4 to n = 1 4. n = 2 to n = 1 5. n = 3 to n = 1 Explanation: The longest wavelength is produced in the case where the least amount of energy is released. That is, in this case, from n = 4 to n = 3 . 003 10.0 points In an experiment, light of a particular wave- length is incident on a metal surface, and electrons are emitted from the surface as a result. To produce more electrons per unit time but with less kinetic energy per electron, the experimenter should do which of the follow- ing? 1. Increase the intensity and decrease the wavelength of the light 2. Increase the intensity and the wavelength of the light correct 3. None of these would produce the desired result. 4. Decrease the intensity and increase the wavelength of the light 5. Decrease the intensity and the wavelength of the light Explanation: In photoelectric effect, the number of elec- trons emitted per unit time is proportional to the intensity of the incident light. To pro- duce more electrons, the experimenter should increase the intensity of the light. The maximum kinetic energy of the emitted gilbert (amg3448) – HW13 – tsoi – (57210) 2 electrons is determined by K = hf- W = h c λ- W ....
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## This note was uploaded on 03/29/2012 for the course PHY 302l taught by Professor Morrison during the Spring '08 term at University of Texas.

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HW13-solutions - gilbert (amg3448) – HW13 – tsoi –...

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