# DeBroglie wavelength based on kinetic energy

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1. Feb 11, 2017

### Cocoleia

1. The problem statement, all variables and given/known data
I am working on a problem similar to this one:

In this solution, I do not understand what mc is, can someone explain? Also, would I follow the same type of steps if I have the kinetic energy of a photon and I need it's wavelength?

2. Relevant equations

3. The attempt at a solution

2. Feb 11, 2017

### Staff: Mentor

Looks like a typo. It should also be $m_e$, the rest mass of the electron.

Photons have no rest mass. Setting it to zero in the equation in your problem yields p = K/c, where K is the energy of the photon. That's a valid result linking energy and momentum for a photon. To get at the wavelength appeal to the Planck relationship, $E = h \nu$.