CdS photodetector is irradiated by light with the wavelength

CdS photodetector is irradiated by light with the wavelength of 420nm and intensity of 50 Wm-2. If the band gap of CdS is 2.4 eV and all electron-hole pairs are extracted without recombination, what is current density of this photodetector?

Solution

Current density of Photo detector (J_x) = q×n_o×_x

                   Let, q (wave length) = 420 nm = 420×10^-9 m

                           n_o (Intensity) = 50 W/m²

                          _x (Band gap) = 2.4 ev

Current density (J_x) = 420×10^-9 × 50 × 2.4

                                = 5.04 ×10^-5