# Photoelectric Effect - Wavelength of a Photon

1. May 7, 2009

### BioBabe91

1. The problem statement, all variables and given/known data
Calculate the wavelength of a photon having the same momentum as an electron
moving at 1.0  106 m/s.
The answer is supposed to be 0.73 nm.

2. Relevant equations
Ek = (m*v^2)/2
Ek = hf - W
p = E/c = hf/c = h/$$\lambda$$

3. The attempt at a solution
I first found Ek using the kinetic energy formula, using the speed of the electron given in the question and the mass of the electron.
I can't quite figure out where to go next.

2. May 7, 2009

### dx

This problem has nothing to do with the photoelectric effect. Find the momentum of an electron moving at the speed given, substitute it in p = h/λ, and solve for λ.

3. May 7, 2009

### BioBabe91

It is in the photoelectric effect section of the book, though.

Alright, thanks.