Light of intensity $10^{-5} \;wm^{-2}$ falls on a sodium photocell of surface area $2 cm^2$ Assuming that the top 5 layers of sodium absorb the incident energy, estimate the time required for photo electric emission in the wave picture of radiation . The work function of the metal is given to be about 2 ev . What is the implication of your answer ? Effective atomic area $=10^{-20} m^2$

Question

$\begin{array}{1 1} t= 1.6 \times 10^7 s \\t= 1.6 \times 10^7 min \\ t= 16 \times 10^7 s \\ t= 16 \times 10^7 min \end{array}$