• question_answer Wavelength of a 1 keV photon is $1.24\times {{10}^{-9}}m$. What is the frequency of 1 MeV photon           A) $1.24\times {{10}^{15}}Hz$    B) $2.4\times {{10}^{20}}Hz$ C) $1.24\times {{10}^{18}}Hz$    D) $2.4\times {{10}^{23}}Hz$

[b] $E=h\nu \Rightarrow \nu =\frac{E}{h}=\frac{1\times {{10}^{6}}\times 1.6\times {{10}^{-19}}}{6.6\times {{10}^{-34}}}$ $=2.4\times {{10}^{20}}Hz$