(adsbygoogle = window.adsbygoogle || []).push({}); 1. The problem statement, all variables and given/known data

Supopse that a 100 W source radiates light of wavelength 600 nm in all directions and that the eye can detect this light if only 20 photons per second enter a dark adapted eye having a 7 mm diameter pupil. How far from the source can the light be detected under these conditions?

2. Relevant equations

[tex]E = hf = hc/\lambda[/tex]

3. The attempt at a solution

I am having a hard time finding a relationship between the 100 W source and a distance. At what rate do the photons die off?

I can calculate the energy per photon: [tex]E = hc\ 600nm[/tex] but with that information, I still don't see a way factor distance in there.

Anyone have some hints?

how I can figure out at what rate it will dissipate over a distance.

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# Homework Help: Photon Intensity

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