A certain dye absorbs light of λ=4000  Ao and then fluoresces light of 5000  Ao. Assuming that under given conditions 50% of the absorbed energy is re-emitted out as fluorescence, calculate the ratio of number of quanta emitted out to the number of quanta absorbed.

Eemitted  =50100 ×  EabsorbedNo.  of  emitted  photons  ×  Energy  of  emitted  photon=                                         50100×   No.  of  absorbed  photon  ×  Energy  of  absorbed  photon.∴    ne ×   124005000 =50100 ×  na × 124004000(since E=hCλ; hC =12400eV.Ao)∴    nena=58.