A gas absorbs a near U. V. photon of wavelength 300 nm and then emitted as 2 photons. One photon is red which has a wavelength of 760 nm. Calculate the wavelength of second photon.

λ1 (U.V. light) =300nm=300×10−9m;λ2(red light) =760nm=760×10−9m.For U.V. light, E=hcλ=hc300×10−9m                           …(i)For red light, E1=hcλ1=hc760×10−9m                           …(ii)Energy associated with second photon, E2              Now E=E1+E2.hc300×10−9m=hc760×10−9m+hcλ2hc300×10−9m=hc1760×10−9m+1λ21λ2=1300×10−9m−1760×10−9m=760×10−9m−300×10−9m300×10−9m×760×10−9m=460×10−9m228,000×10−18m2λ2=228000×10−18m2460×10−9m=4.96×10−7m=4.96×10−7m×1nm10−9m= 496 nm.