1. I need some clarification that I answered this question properly What is the wavelength of an electron of energy 5.0 eV? Would I just use E=mc^2 to find the mass and then wavelength = h / mv to find the wavelength? 2. This question is also giving me problems By what potential difference must a proton (Mo = 1.67 * 10^-27 kg) be accelerated to have a wavelength of 0.0011 nm? Would I first use v = h / m * wavelength to find the velocity? And then eV = 1/2 mv^2 to find the voltage?