Engineering question: How does the electron gun shoot one electron at a time to the double slit target? How was this possible when the experiment was done 100 years ago? How is this done with photons? Is there a check to ensure only one electron/photon is arriving at the target?


1 Answer 1


In practice, you set the intensity of the source to a level at which it is unlikely that there is more than one electron or photon in the apparatus at a time. It doesn't have to be perfect.

  • $\begingroup$ For photons there are single-photon sources that can truly only emit one photon at a time. $\endgroup$
    – Jon Custer
    Commented Dec 11, 2022 at 1:42
  • $\begingroup$ @JonCuster True, but the classic experiments didn't use them and they are not necessary. $\endgroup$
    – John Doty
    Commented Dec 11, 2022 at 1:51
  • $\begingroup$ Agreed, just pointing out that they exist. $\endgroup$
    – Jon Custer
    Commented Dec 11, 2022 at 1:54

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