Hi. I hope someone can help. Here is the problem: [Pennies are made of zinc coated with copper. Copper has a work function of 4.7eV. The ozone layer blocks nearly all solar radiation with wavelength shorter than 320nm, but a very small amount of 200nm light still manages to reach the Earth's surface. Can direct sunlight produce photoelectrons from a penny?] I converted the 4.7eV into joules: 4.7eV * 1.602e-19J = 7.529e-19J I found the minimum kinetic energy needed to for the electrons to escape from the copper: KE = e * V_o => 1.602e-19 * 7.529e-19 = 1.206e-37J I'm thinking that I need to use the 200nm to find out whether the kinetic energy I calculated will be produced by the sunlight, but I don't see how to do that.