I know this might be a stupid question but...

[physicshelpplease]

Whats the difference between the Energy, E=hf of an electron and Energy, E=p^2/(2m) of an electron? please someone help. thanks

[mark_alec]

E=hf is the energy formula for photons, not electrons.

[paulsterio]

I can't really explain this question because what do you mean by the "difference"?

This is a typical VCE Physics-esque question the type that gets asked quite frequently because multiple formulas are taught by rote without any real sort of explanation or derivation. What in the world is:



It looks like it comes from:



so

Just do a substitution and you get that formula. This is why I honestly don't think you should be learning pre-made formulae, always calculate your core information then use that to find other things. If you have momentum, use that to find velocity and use velocity to find Energy.

Either way, is used for photons, however, the energy of ejected electrons is the same as the photons minus the work function, but I don't think that's what you're even asking.