Genecks Posted March 30, 2007 Share Posted March 30, 2007 My chemistry book is covering some basics of energy and photons. I worked most of the problems, but I couldn't figure this one out: If the laser emits [math](1.3)(10^{-19}) J[/math] of energy during a pulse, how many photons are emitted during the pulse? Link to comment Share on other sites More sharing options...
swansont Posted March 30, 2007 Share Posted March 30, 2007 My chemistry book is covering some basics of energy and photons. I worked most of the problems, but I couldn't figure this one out: You have the wavelength or frequency? That will tell you the energy per photon. [math]E = h\nu = hc/\lambda[/math] Link to comment Share on other sites More sharing options...
Genecks Posted March 30, 2007 Author Share Posted March 30, 2007 [math](4.69)(10^{14}s^{-1})[/math] I believe that's the frequency. I'm not too sure what variables I'm suppose to be using. I know the answer is [math](4.2)(10^{16})[/math], but I don't see how. Link to comment Share on other sites More sharing options...
swansont Posted March 30, 2007 Share Posted March 30, 2007 h = 6.63 x 10^-34 J-s That gives 3.1 x 10^-19 J per photon, which is less than the pulse energy, so something is very wrong. Using your answer, the pulse energy should be 1.3 x 10^-3 J. Typo, or transcription error perhaps? Link to comment Share on other sites More sharing options...
Genecks Posted March 30, 2007 Author Share Posted March 30, 2007 Probably. What I'm reading seems to be illogical. It seems as if the author uses improper pronoun-antecedent usage. Link to comment Share on other sites More sharing options...
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