A photon of wavelength 250 nm, absorbed by a substance was subsequently emitted as two photons. The first photon had a wavelength of 600 nm. What was the wavelength of the second photon?

Explanation

Energy of absorbed photon, `E=hc//lambda`
Energy of first photon emitted, `E_(1)=hc//lambda_(1)` , Energy of second photon emitted, `E_(2)=hc//lambda_(2)`
`E=E_(1)+E_(2) or (1)/(lambda) =(1)/(lambda_(1))+(1)/(lambda_(2)) and (1)/(lambda_(2))=(1)/(lambda)-(1)/(lambda_(1))" i.e. "(1)/(lambda_(2))=(1)/(250) - (1)/(600)`
Wavelength of second photon emitted,
`lambda_(2)=(250xx600)/(600-250)=428.57nm`