Why Does Kinetic Energy of Electron in Photoelectrics Follow Classical Approach?

[Azmodan]

Hello friends.

I was just wondering why in photoelectrics, the kinetic energy of an electron released from a certain metal after being struck by a photon follows the classical approach and not the relativistic. For example...

E_photon = (Planck_const)(frequency) = (Work function) + (1/2)(mass_electron)(u^2)

instead of

E_photon = (Planck_const)(frequency) = (Work function) + ((1 - ((u/c)^2)))^(-1)) - 1)(mass_electron)(c^2)

I've read several texts, including my university's text and Serway's text but the answer isn't really there. Thanks in advance!

 

[PeterDonis]

I was just wondering why in photoelectrics, the kinetic energy of an electron released from a certain metal after being struck by a photon follows the classical approach and not the relativistic.

AFAIK all the photoelectric experiments that have ever been done have involved highly non-relativistic photoelectrons, so the classical formula works fine, but strictly speaking, it is an approximation and the relativistic formula is the strictly correct one.

 

[Azmodan]

Cool, thanks Peter.