Finding Kinetic Energy of an Electron with 100keV X-Ray Wavelength

[asdf1]

how do you find the kinetic energy of an electron whose de Broglie wavelength is the same as that of a 100keV x-ray?

 

[El Hombre Invisible]

Since the de Broglie wavelength is given by the momentum of the particle, I guess you would first determine the momentum p of the photon: p = E/c (I think), then find the kinetic energy of the electron via 0.5p^2/m, where m is the electron mass.

 

[asdf1]

it's not a photon, but can you still use that formula?

 

[El Hombre Invisible]

Yes, you can use the de Broglie formula h/p to find the wavelength of an electron or a photon. The difference between the two comes in determining p. For an electron, p = mv. For a photon, p = E/c.

So if your photon has energy E = 100 keV, convert this to Joules and use p = E/c to find the momentum of the photon.

If the de Broglie wave of the electron has the same wavelength, it must have the same momentum p.

 

[asdf1]

ok, thanks!