1. The problem statement, all variables and given/known data Through what potential difference should you accelerate an electron from rest, such that it's de Broglie wavelength will be 0.1 nm. 2. Relevant equations E = hf λf = c 3. The attempt at a solution My Thinking was; E = hf E = hλ/c E= 6.626e-34 * 1e-10/3e8 which turned out 2.21e-58 J, which I'm pretty sure is wrong. Anyone with some ideas or a worked solution would be fantastic :D Regards all, Will.