[LawlKake]

"Suppose that a particular sample of H atoms has all of the atoms in the n=5 state. Photons emitted from the sample are used as a light source to dislodge electrons from the surface of Mg(s). What is the minimum de Broglie wave length of an ejected electron? Work function for Mg(s) is 5.86e-19 J. Mass electron = 9.109e-31 kg."

My attempt:

Code: [Select]

KE = 1/2mv^2
5.86e-19 = 1/2 9.109e-31 v^2
v = 1134301.365
wavelength = h/mv
                = h / 9.109e-31 x 1134301.365
                = 6.41e-10 m

Apparently that's not the right answer (Online Quiz).

[LawlKake]

Yes, I've tried simply calculating the wavelength using W = hf = hc/lambda, wavelength = 3.39e-7 m and submitting it as an answer, but it was not correct.

[Borek]

You need to use two equations - Rydberg equation for energy of photon emitted by hydrogen, and equation for photoelectric effect.