As photons are massless thus by $E=mc^2$, the energy should be zero right? or should it be? I would be pleased to be corrected
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1Does this answer your question? Does $E = mc^2$ apply to photons? – anna v Jul 06 '22 at 16:23
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Yes Thanks, it does answer! – Sciencenium Jul 07 '22 at 10:52
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The full formula is $E= \sqrt{c^2p^2+m^2 c^4}$, so for massless particles $E= pc$. The momentum $p$ of of photon is given by $p= h/\lambda$, so, from $\lambda \nu=c$ where $\nu$ is the frequency, we have $E= h\nu$ .
mike stone
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From E=hν, plank's constant is fixed, so does every wavelength of light has a fixed specific energy? – Sciencenium Jul 06 '22 at 12:36
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Yes. Every photon has energy proportional to its frequency. $N$ photons of the same frequency have a total energy of $E=Nh\nu$. – mike stone Jul 06 '22 at 12:39
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