Question

The X-ray coming from a Coolidge tube has a cutoff wavelength of 80 pm. Find the kinetic energy of the electrons hitting the target.

Answer 1

Given:
Cutoff wavelength of the Coolidge tube, $\lambda$ = 80 pm
Energy of the electron hitting the target $\left(E\right)$ is given by
$E=\frac{hc}{\lambda }$
Here,
h = Planck's constant
c = Speed of light
$\lambda$ = Wavelength of light

$$\begin{gathered} \therefore E=\frac{1242\mathrm{eV}-\mathrm{nm}}{80\times {10}^{-3}} \\ \Rightarrow E=\frac{1242\times {10}^{-9}\mathrm{eV}}{80\times {10}^{-12}} \\ \Rightarrow E=15.525\times {10}^3\mathrm{eV}\approx 15.5\mathrm{keV} \end{gathered}$$