Answer
$3.022\times10^{-19}J/photon$
Work Step by Step
The energy per photon is given by:
E = hν = $\frac{hc}{λ}$
We know:
h = $6.626\times10^{-34}Js$
c = $2.997925\times10^{8}ms^{-1}$
λ = 6573 Å = $6573\times10^{-10}m$
Thus:
E = $\frac{6.626\times10^{-34}Js\times2.997925\times10^{8}ms^{-1}}{6573\times10^{-10}m} = 3.022\times10^{-19}J$
