question: A certain proton needs to have a lamba of 0.0055 x 10^-9m. What potential difference must this proton be accelerated to achieve this wavelength? what i know: im assuming that what we need to find in this question is the amount of kinetic enegry needed to achieve such a lambda. E = hv / y y will represent lambda i also know that Ek = eV <--- potential difference and that Ek = 1/2mv^2 so eV = 1/2mv^2 and v is = E x lambda / h so eV = 1/2m (eV x lamba / h) ^2 am i on the right track here or am i completly lost??