ch38-p011 - 11. (a) We assume all the power results in...

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where E = hf and f = c / λ are used. Here h is the Planck constant, f is the frequency of the emitted light, and λ is its wavelength. Thus, R P hc == × ×⋅× λ 589 10 100 6 63 10 300 10 296 10 9 34 8 20 mW Js m /s photon / s. ch bg c hc h .. . (b) Let I be the photon flux a distance r from the source. Since photons are emitted uniformly in all directions, R = 4 π r 2 I and () 20 7 42 2.96 10 photon/s 4.86 10 m. 4 4 1.00 10 photon/m s
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