The greater the number of
energy quanta available, the greater is the number of
electrons absorbing the energy quanta  and greater,
therefore, is the number of electrons coming out of
the metal (for n > n0) This explains why, for n > n0,
photoelectric current is proportional to intensity ·
In Einstein’s picture, the basic elementary process
involved in photoelectric effect is the absorption of a
light quantum by an electron This process is
instantaneous