10-3 walt of 5000 Ao light is directed on a photoelectric cell. If the current in the cell is 0.16 μA, the percentage of incident photons which produce photo electrons, is

Energy of each photo =hc/λ=124005000eV=2.48eV=2.48×e Joule Number of photons striking the target metal p2.48×e=10-32.48×eS-1Number of electrons affected per second from the metal surface =ie=0.16×10-6e∴ Efficiency =0.16×10-6/e10-3/2.48×e×100%=0.16×10-6×2.4810-3×100%=0.04%