Question

The wavelength of a 1 keV photon is 1.24 nm. The frequency of 1 MeV photon is:

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

Answer 1

Answer: (B)

$2.4\times {{10}^{20}}Hz$

Answer 2

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