Question

An electron beam in an X-ray tube is accelerated through 40kV and is incident on a tungsten target. What is the shortest wavelength emitted by the tube? 

Answer 1

$\lambda_{min}=\frac{hc}{eV}=\frac{6.62\cdot10^{-34}\cdot3\cdot10^8}{1.6\cdot10^{-19}\cdot40000}=0.3\cdot10^{-10}\ (m)$