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It would be logical to think that the more electrons are ejected from an atom, the harder it is to eject more.

I just learned about photoelectric effect experiment. The book is kinda telling me the threshold frequency never changes even as more and more electrons are ejected.

But it is very counterintuitive because 1. Screening effect is reduced, meaning stronger nuclear attraction, more force, more energy required to ionize that electron. 2. Because the atom is now ionized, there is then electrostatic force between the atom and any electron attempting to get out.

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The metal plate is typically attached to a circuit which collects the ejected electrons making the system net neutral overall just with a current flowing. Also they are usually more easily ejected because the plate is at a potential attached to a battery.

However, if the plate were suspended by an insulator in a vacuum and it continuously lost electrons then indeed each electron subsequently ejected will have less kinetic energy than the one preceding it by a tiny amount.

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  • $\begingroup$ Can you explain perhaps with some math why there is less KE to each subsequent electron ejected? $\endgroup$
    – most venerable sir
    Commented Aug 7, 2015 at 13:45
  • $\begingroup$ Do they work just like capacitor? $\endgroup$
    – most venerable sir
    Commented Aug 7, 2015 at 14:45

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