1. The problem statement, all variables and given/known data In an electrom microscope we wish to study paprticles of diameter about 0.10 µm (about 1000 times the size of a single atom). What should be the de Broglie wavelength of the electrons? Through what voltage should the electrons be accelerated to have that de Broglie wavelength? 2. Relevant equations ? 3. The attempt at a solution I know the equation wavelength = h / p, but that doesn't seem to get me anywhere, but that's the only equation for the de Broglie wavelength I know. Therefore, I should look for ways to find p by using the diameter of the particle, but a particle's size shouldn't matter towards its momentum. So is there are a couple of equations I'm missing, that can get me from the one given quantity of diameter to the wavelength?