Photoelectric Effect

The reason the charge is lost is that the electrons are gaining sufficient energy to be ejected from the sorface of the zinc plate. Electrons would be ejected from the +ve gold leaf on the Gold Leaf Electroscope but would be immediately attracted back.

Albert Einstein tried to explain these observations. His first suggestion was that the enegy supplied by the light to the electrons is related to the frequency of the light rather than the intensity. His next suggestion was that light arrives as particles, or packets of energy rather than a continuous stream or flow of energy. If it was a wave supplying continuous energy, eventually the electrons would absorb enough ro be ejeted. Each ejectron (photoelectron) recieves its energy from a single packet , otherwise an intense beam of low energy packets could supply sufficient energy. The energy of these packets is proportional to the frequency such that E=hf. These packets are called photons.

E=hf
unit = Js
h=planck's constant = 6.63*10^-34 (in formula booklet)