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A 100W sodium lamp radiates energy unifo...

A 100W sodium lamp radiates energy uniformly in all directions. The lamp is located at the centre of a large sphere that absorbs all the sodium light which is incident on it. The wavelength of the sodium light is 589nm. (a) What is energy associated per photon with the sodium light? (b) At what rate are photons delivered to the sphere?

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(a) Energy associated per photon with the sodium light is,
`E=(hc)/lambda=(6.63xx10^(-34)xx3xx10^(8))/(589xx10^(-9))=3.38xx10^(-19)J , (b) n=P/E=100/(3.38xx10^(-19))=3.0xx10^(20)"photons"//s`
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