work function and Kinetic energy
What actually is the work function because books and videos don't explain it properly they always waffle. Is it the energy needed for the electron to LEAVE THE METAL or for it to BREAK THE BOND HOLDING IT THERE. Also, does the kinetic energy of the photoelectron equal to hf minus the work function and the range of kinetic energies is due to deeper electrons colliding with the metal surface? e.g. electrons at the top will have MAX KE and the ones at the bottom have MIN KE since they have to travel further to leave so there's more collisions.
Please clear this up for me because I'm always getting confused with this and again videos and books don't really explain it properly. Thank you.
Please clear this up for me because I'm always getting confused with this and again videos and books don't really explain it properly. Thank you.
Original post by fares22
What actually is the work function because books and videos don't explain it properly they always waffle. Is it the energy needed for the electron to LEAVE THE METAL or for it to BREAK THE BOND HOLDING IT THERE. Also, does the kinetic energy of the photoelectron equal to hf minus the work function and the range of kinetic energies is due to deeper electrons colliding with the metal surface? e.g. electrons at the top will have MAX KE and the ones at the bottom have MIN KE since they have to travel further to leave so there's more collisions.
Please clear this up for me because I'm always getting confused with this and again videos and books don't really explain it properly. Thank you.
Please clear this up for me because I'm always getting confused with this and again videos and books don't really explain it properly. Thank you.
"leave the metal" and "break the bond holding it there" are the same thing. The work function is just how much energy you need to rip the electron out of the metal. If you break the electric field attractive force with enough energy, that is the same as leaving the metal.
"deeper" electrons don't matter. You can remove any electron from a metal where the electron is part of the delocalised lattice of electrons. e.g. if you have a bar of gold, you can remove any electron which is a delocalised (or "conduction" electron). But you can't remove an electron that is in the 1s orbital of a gold atom.
If the work function of a metal changes, it's usually due to heating or cooling the metal. But typically you'll just have one value for this in an exam and I dont think thermal conduction fields are taught at A-Level.
The Kinetic energy is just (energy of photon) - (work function). or hf - phi. The position of the electron or its travel distance do not matter. The only thing that affects Kinetic energy is the work function and the frequency of the photon.
Sometimes ejected electrons have energy lower than this, but this will be because the electron collided with something, or lost some of its energy through heat radiation, or something similar.
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