1. The problem statement, all variables and given/known data http://www.strings.ph.qmul.ac.uk/~russo/QP/r06QPHYEX.pdf [Broken] Question 3. 3. The attempt at a solution I can easily derive the equation I need, which is: lamda = h/p Which after some playing around with K.E =1/2mv^2 etc we obtain: lambda (de brogile) = h/SQRT(2mKE) Here is the data we are provided with in the exam (see sheet 1): http://www.strings.ph.qmul.ac.uk/~russo/QP/week6.pdf [Broken] Everythings in eV and MeV, I plug in the values constantly, tried converting h to joules, and the electron mass to kg etc, but no avail as I don't think I know what Im doing with it, and I can't seem to obtain the real answer which is: 1.2 x10^-9m Anyone explain how to do this quickly? I understand the theory behind this top notch but missed on how to use eV etc. THANKS.