Photoelectric Effect - Wavelength of a Photon

[BioBabe91]

Homework Statement

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.

Homework Equations

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

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.

 

[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.

 

[BioBabe91]

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

Alright, thanks.