Question

The wavelength of a 1 keV photon is $1.24\times 10^{-9}$ m. What is the frequency of 1 MeV photon?

• A. $2.5\times 10^{15}$ Hz
• B. $2.5\times 10^{20}$ Hz
• C. $1.24\times 10^{15}$ Hz
• D. $1.24\times 10^{20}$ Hz

Answer 1

Answer: (B)

$\frac{hc}{\lambda }=1000eV$
$hv=10^{6}eV$
$\Rightarrow \frac{\lambda \nu }{c}=1000eV$
$\Rightarrow v=\frac{3\times 10^8\times 1000}{1.2\times 10^{-9}}=2.5\times 10^{20}Hz$