# Homework Help: Quantum mechanics.

1. Aug 22, 2010

### pyxolo

Hi there.
I am a student from Spain and I am about to join the University but I have to pass physics at High School.

Here It is:

The work of extracting an Eletron in a metal is 3.8 eV. Calculate the minimum frequency needed to start the electron.

This is what I did.

$$$E = \phi + Ec$$$

Regarding to Einstein's equation of photoelectric effect:

$$$h\nu = h\nu _0 + \frac{1}{2}mv^2$$$

When I got to this point, I assumed that the electron's velocity would be zero and then: