Answer:
601 nm
Explanation:
Energy of photon having wavelength of λ nm
= [tex]\frac{1244}{\lambda}[/tex]eV
Energy of 249 nm photon
=[tex]\frac{1244}{249}[/tex]
=4.996 eV
Similarly energy of 425nm photon
=[tex]\frac{1244}{425}[/tex]
=2.927 eV
Difference = 2.069 eV.
This energy will give rise to another photon whose wavelength will be
λ = [tex]\frac{1244}{2.069}[/tex]
= 601 nm.
