1. The problem statement, all variables and given/known data Ok, question is: " Calculate the de Broglie wavelength for an electron that has kinetic energy a)50.0 eV b) 50.0 keV and c) 3.00 eV d) What If? A photon has energy 3.00 eV. Find its wavelength. 2. Relevant equations E=hf 1/2 m(v^2) *lambda* = planck's constant / momentum 3. The attempt at a solution Was just going to use E = hf then find wavelength from f, but realized that v is unknown unless I can use classical equation K=1/2m(v^2) but I was not sure I can do this??? If I can, problem is easy, if I can't... will need some help... Thanks!