1. The problem statement, all variables and given/known data Calculate the de - Broglie wavelength associated with a neutron moving with energy of 2ev .( mass of proton mp= 1.67*10^-27 kg ) 2. Relevant equations Wavelength= nh/ 2π KE = eVs = 1/ 2mv^2 eVs=hf Wavelength= v*f 3. The attempt at a solution To calculate the wavelength at first I required velocity that I got from second equation. I substituted mass of proton since its equal to that of neutron. Then I got the frequency from third equation and put it in equation fourth. But I didn't get the required answer. De- Broglie wavelength is associated with first equation . so I am confused with it I will really appreciate your help.