Energy of a Photon --- EK

[Dr Gerrard]

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EK Page 142.

E=hf

Warning: Do not be misled by this equation: This equation gives the energy per photon. It turns out that if we double the fequency, we also double the number of photons increasing the intensity by a factor of four as expected.

All right, I do not understand this last sentence. Anyone want to help me out?

 

[sv3]

in Ek (I use TPR as well and they dont mention it) the intensity of a wave is proportional to the square of the frequency

not sure why Ek bothers to mention some things....perhaps to make it sound like they came up with something original as opposed to copying kaplan and princeton?

well there you go anyway.

 

[chemtopper]

E =nhf
here n is the number of moles of photons.
when n=1
E=hf
This is the energy per photon
If you double the photons
n=2
E= 2hf
Now let us see how Intensity is related to energy of photons and frequency .
I ∝ E

I ∝ f2
but if you double the frequency ,intensity will become four times.
Frequency is the no of cycles per unit sec,so if we double frequency it means we have doubled the no of cycles per sec i.e we have doubled the photons per sec .
E = 2h2f= 4hf
I ∝ E so intensity will become four times .
I hope now things are clear .