Question

The Fermi enrgy of copper is 7 eV. (use h = 6.6 ×10−34JHz−1 , 1eV = 1.602×10−19J, me=9.1×10−31 kg ).
The de Broglie wavelength of the electron is?

Answer 1

$$\lambda=\frac{hc}{E}\\\lambda=\frac{1239.84}{7}=177\ nm$$