Question

The energy of a photon of light with wavelength $5000\, \mathring{A}$ is approximately $2.5\, eV$. This way the energy of an $X$ -ray photon with wavelength $1\, \mathring{A}$ would be

• A. $2.5 / 5000\, eV$
• B. $2.5 /(5000)^{2}\, eV$
• C. $2.5 \times 5000\, eV$
• D. $2.5 \times(5000)^{2}\, eV$

Answer 1

Answer: (C)

$E \propto \frac{1}{\lambda}$
$\Rightarrow \frac{2.5}{E'} =\frac{1}{5000}$
$\Rightarrow E'=(2.5) \times 5000\, eV$