The energy carried by a single photon is given by
[tex]E=hf[/tex]
where h is the Planck's constant and f is the frequency of the photon.
The photon of our exercise has a frequency of [tex]f=1.7 \cdot 10^{17} Hz[/tex], therefore its energy is
[tex]E=hf=(6.63 \cdot 10^{-34}Js)(1.7 \cdot 10^{17} Hz)=1.1 \cdot 10^{-16} J[/tex]
