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In photo electric effect ,if electrons escape, shouldn't that leave the metal positively charged ??. How does it maintain its electrical neutrality ? And if it doesn't , shouldn't the work function increase as a positive metal piece would pull electrons more strongly and more energy would be required.

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Metals are conductors. As electrons escape, new electrons easily flow from ground into the metal to maintain neutrality. If you have an insulator in vacuum, it does begin to gain a positive charge as electrons are removed, which causes an increase in the apparent workfunction.

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  • $\begingroup$ in your theory, a metal, floating in space, light shone on it, could not create the photoelectric effect, because it is not connected to the ground. Where do the electrons then come from, to replace the old, knocked off electrons? $\endgroup$ – Árpád Szendrei May 25 '19 at 21:35
  • $\begingroup$ Ok, if it's floating in space that's another story. I was thinking about a real setup in a lab. This effect is noticeable in photoelectron spectroscopy; charging occurs in insulating samples that must be neutralized with an electron gun. $\endgroup$ – HiddenBabel May 25 '19 at 22:09
  • $\begingroup$ But even in vacuum, as the charge increases, free electrons/ions flying around become more attracted to the sample to partially neutralize it (this would happen in space as well). $\endgroup$ – HiddenBabel May 25 '19 at 22:13
  • $\begingroup$ @HiddenBabel Say we somehow remove those particles $\endgroup$ – user232243 May 26 '19 at 3:13
  • $\begingroup$ @user232243 Then your sample would continue to charge until the energy of the photons in your light source is insufficient to remove any more electrons $\endgroup$ – HiddenBabel May 26 '19 at 3:29

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