[er4444]

A minimum energy of 7.21e-19J is required to produce the photoelectric effect in chromium metal.

b. Light with a wavelength of 2.50e-7m falls on a piece of chromium metal in an evacuated glass tube. What is the minimum de Broglie wavelength of the emitted electron?

So we never learned anything about de Broglie. When I look up what it means the answers are really abstract and I don't understand what I'm supposed to even do for this.

[sjb]

What is the energy of a photon with wavelength 2.5 x 10^-7m?