practiceexam15 - City College, Chemistry Department...

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City College, Chemistry Department Chemistry 10301, sections T and T2, Prof. T. Lazaridis Third Midterm exam, Nov 30, 2006 Name (last name first): ___________________________________ I.D. Number: ____________________________________________ Workshop leader:________________________________________ Note: There are 10 questions in this exam. Fill in your answer in the blank space provided immediately following each question. 1/2 point will be subtracted every time you report a numerical result with an incorrect number of significant figures. Useful data: Speed of light : 2.9979 X 10 8 m/s Planck's constant : 6.626 X 10 -34 Js E n = -2.179 X 10 -18 J/n 2 1. (5) A diode laser emits at a wavelength of 987 nm. All of the radiation it emits is absorbed in a detector which measures a total energy of 0.52 J over a period of 32 sec. How many photons per second are being emitted by the laser? 0.52 J/ 32 sec = 0.016 J/sec E = h c / λ = 6.626 X 10 -34 Js X 2.9979 X 10 8 (m/s) / 987 10 -9 m = 0.020 10 -17
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practiceexam15 - City College, Chemistry Department...

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