Follow the steps outlined in this problem to estimate the time lag (predicted classically but not observed experimentally) in the photoelectric effect. Let the intensity of the incident radiation be 0.01 W/m². 

(a) If the area of the atom is (0.1 nm)², find the energy per second falling on the atom. 

(b) If the work function is 2.0 eV, how long would it take (classically) for enough energy to fall on this area to liberate one photoelectron? 

(c) Explain briefly, using the photon model, why this time lag is not observed.