1. The problem statement, all variables and given/known data Light illuminates a metallic surface with work function of 1.20 eV. It takes 1.0 V of retarding potential to stop all of the photoelectrons from reaching the opposite plate. Find the maximum speed of the photoelectrons. 2. Relevant equations hf = w hf = w + Ek 3. The attempt at a solution First work function = 1.20eV(1.60x10-19 J/eV) = 1.92x10-19 J Not really sure how to do this problem... but giving it a go here: First, hf = w f = w/h f = 1.92x10-19 J / 6.63x10-34 Js f = 2.9x1014 Hz Now i got the frequency, i assume i use: hf = w+ Ek Ek = hf - w 1/2mv2 = hf - w Is this correct so far? If yes do i just plug in the numbers and solve for "v" also not really sure what to do with the retarding potential?