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?

  • 1
    $\begingroup$ 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
  • 2
    $\begingroup$ 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

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.

  • 2
    $\begingroup$ Always trust answers about photons from the Photon itself $\endgroup$ – Run like hell Dec 23 '17 at 16:18

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service, privacy policy and cookie policy

Not the answer you're looking for? Browse other questions tagged or ask your own question.