So I have a question like this :
Cesium has a work function of 1.8 eV. When light of wavelength 400 nm falls on the cathode of a photocell of area 1.2 cm^2, only 1 out of every 5 photons succeeded in ejecting an electron. The photoelectric current is 0.25 Calculate the :
(i) Rate of emission of the photoelectrons from the cathode
(ii) Intensity of the incident light
I know the formula of intensity of incident light is But i don't know how to apply it here
Please help me..