1.5 mW of 400 nm light is directed at a photoelectric cell. If 0.1 % of the incident photons produce photoelectrons, find the current (in μA) in the cell.

Number of photons incident per second                = Power  Energy of one photon =P(hc/λ)=PλhcNumber of electrons emitted per second = 0.1% of                 Pλhc=Pλ1000hc∴Current = Charge (on photoelectrons per second)                =Pλe1000hc=1.5×10−3400×10−91.6×10−19(1000)6.63×10−343×108=0.48×10−6A=0.48μA