6.radiation key

6.radiation key - Chem 105 Nielson Recitation 9/25/07...

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Chem 105 Nielson Recitation 9/25/07 Electromagnetic radiation Photoelectric effect Atomic spectra Bohr atom 1. The yellow light given off by a sodium vapor lamp used for public lights has a wavelength of 589 nm. a. What is the frequency of this radiation? Ans. 5.09 x 10 14 s -1 b. What is the energy of one quantum or photon? Ans. 3.37 x 10 -19 J c. If in an hour’s time, the lamp emits light with a total energy of 27 J, how many photons have been emitted? Ans. 8.0 x 10 19 photons 2. Molybdenum metal must absorb radiation with a minimum frequency of 1.09 x 10 15 s -1 before it can emit an electron from its surface via the photoelectric effect. a. What is the minimum energy required to produce this effect (the threshold energy)? Ans. 7.22 x 10 -19 J b. What wavelength radiation will provide a photon of this energy? Is this visible light? Ans. 275 nm. No, this is not visible light. The range for visible light is 400-700 nm.
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c. If molybdenum is irradiated with the light of wavelength 120. nm, what is the
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This note was uploaded on 12/09/2009 for the course CHEM 105 taught by Professor Macedone during the Spring '07 term at BYU.

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6.radiation key - Chem 105 Nielson Recitation 9/25/07...

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