Chapter 38 - Photons and Matter Waves - Problems - Page 1183: 47

$\lambda = 7.77\times 10^{-12}~m$

We can use Equation (38-20) to find the de Broglie wavelength: $K = \frac{h^2}{2m \lambda^2}$ $\lambda^2 = \frac{h^2}{2m~K}$ $\lambda = \sqrt{\frac{h^2}{2m~K}}$ $\lambda = \sqrt{\frac{(6.63\times 10^{-34}~J~s)^2}{(2)(9.109\times 10^{-31}~kg)~(25000~eV)(1.6\times 10^{-19}~J/eV)}}$ $\lambda = 7.77\times 10^{-12}~m$