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Topic: How to find density /m^3 given energy and wavelength  (Read 4962 times)

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Offline s3a

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How to find density /m^3 given energy and wavelength
« on: November 24, 2009, 03:22:17 PM »
"The energy density of starlight in interstellar space is 10^(-15) J/m^3. If the average wavelength of starlight is 500nm, what is the corresponding density of photons per cubic meter of space?"

I'm assuming I need to know that density = mass/volume and E = plank's constant * frequency (E = hv) but I don't know how to get the answer.

Any help would be greatly appreciated!
Thanks in advance!

Offline sjb

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Re: How to find density /m^3 given energy and wavelength
« Reply #1 on: November 24, 2009, 04:59:18 PM »
What is the energy of a photon of light of wavelength 500 nm?

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