Two light sources are used in a photoelectric experiment to determine the work function for a particular metal surface. When green light from a mercury lamp (? = 546.1 nm) is used, a stopping potential of 0.662 V reduces the photocurrent to zero.
(a) Based on this measurement, what is the work function for this metal?
eV
(b) What stopping potential would be observed when using light from a red lamp (? = 684.0 nm)?
V