# DeBroglie wavelength based on kinetic energy

• Cocoleia
In summary, the conversation is discussing a problem involving the kinetic energy of a photon and its wavelength. The first speaker is seeking clarification on the use of "mc" in the solution, which is most likely a typo and should be "m_e" for the rest mass of an electron. The second speaker confirms this and also suggests using the Planck relationship to solve for the wavelength.
Cocoleia

## Homework Statement

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?

## The Attempt at a Solution

Cocoleia said:
In this solution, I do not understand what mc is, can someone explain?
Looks like a typo. It should also be ##m_e##, the rest mass of the electron.

Cocoleia said:
Also, would I follow the same type of steps if I have the kinetic energy of a photon and I need it's wavelength?
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##.

Cocoleia