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A simple but not very simple question please!

If an electromagnetic wave is very very weak, e.g., its energy flux density is less than $h\nu/(\mathrm{m^2\cdot s})$, can there be any photon appearing and can it be detected? $\nu$ is the frequency of the EM wave.

If we consider the EMW is consist of photons, there will be no EMW at all because its energy is even less than a single photon. Am I correct please?

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    $\begingroup$ Note that you may have one photon every hour, for example. Then the flux will be quite small indeed. $\endgroup$ – Blazej Dec 23 '17 at 15:38
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    $\begingroup$ Why do you think 1 square meter times one second would be anything special? $\endgroup$ – Norbert Schuch Dec 23 '17 at 16:25
  • $\begingroup$ thank you for comment,..... im not thinking it special, just an example.....:) $\endgroup$ – justaskphysics Dec 24 '17 at 16:14
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Yes, if you try to detect this radiation, you will only detect it in quanta of $h\nu$. But a detector with area 1 m2 will detect (on average) fewer than one photon per second. For example it might detect 1 photon (on average) every 2 seconds, or one photon every hour.

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    $\begingroup$ Always trust answers about photons from the Photon itself $\endgroup$ – Run like hell Dec 23 '17 at 16:18

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