Problem 5: Imagine that electrons are bound to a metal with a voltage of 2 V (that is, it takes 2 eV of energy
to liberate the electron, or the work function is 2 eV). This metal is illuminated with light of different wavelengths: 1 μm, 0.5 μm, and 0.25 μm.
For which wavelengths is it possible for the light to liberate electrons by the photo-electric effect? And, for the wavelengths that can liberate electrons, what are the kinetic energies and speeds of the liberated electrons? Use the classical (1/2) m v2 formula for kinetic energy. Is that formula okay, or should we be using something more relativistically correct?