Question

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

• A. $1.24\times {10}^{15}Hz$
• B. $2.4\times {10}^{20}Hz$
• C. $1.24\times {10}^{18}Hz$
• D. $2.4\times {10}^{24}Hz$
• E. $2.4\times {10}^{15}Hz,$

Answer 1

Answer: (B)

$f=\frac{c}{\lambda }=\frac{c}{hc/E}=\frac{E}{h}$
$\therefore$ $f=\frac{1\times 1.6\times {10}^{-13}}{6.6\times {10}^{-34}}=2.4\times {20}^{20}Hz$