College Physics (7th Edition)

Recall the equation E= hν = hc/λ. Then, wavelength(λ) = $\frac{hc}{E}$ where h is the Planck's constant, c is the speed of light and E the energy of the photon. Substituting the values, We have λ= $\frac{(6.626×10^{-34}Js)(3.00×10^{8}m/s)}{6.50×10^{-19}J}$=$3.06×10^{-7}m$= 306 nm Referring to the electromagnetic spectrum we can find out that the light with this wavelength is in the ultra violet region.