In a photoelectric effect apparatus, light of wavelength 650 nm illuminates a metal surface. The resulting current is stopped completely when - 0.4 V is applied to the anode.
(a) What is the work function of the metal surface?
(b) What is the maximum kinetic energy of the electron if light of wavelength 450 nm is used?
(c) A 2 W source of this 650 nm light is being detected by a circular detector with radius 2 x 10-3 m. The source radiates uniformly in all directions and the detector is 3 m from the source. How many photons pass through the detector in 1 s?