11 3) (iii) For a given photosensitive material, there exists a certain minimum
cut-off frequency of the incident radiation, called the threshold
frequency, below which no emission of photoelectrons takes place,
no matter how intense the incident light is Above the threshold
frequency, the stopping potential or equivalently the maximum kinetic
energy of the emitted photoelectrons increases linearly with the
frequency of the incident radiation, but is independent of its intensity
(Fig