Due
Rationalised 2023-24
277
Dual Nature of Radiation
and Matter
to negative charge, the emitted electrons are pushed towards the collector
plate by the electric field Hallwachs and  Lenard also observed that when
ultraviolet light fell on the emitter plate, no electrons were emitted at all
when the frequency of the incident light was smaller than a certain
minimum value, called the threshold frequency This minimum frequency
depends on the nature of the material of the emitter plate It was found that certain metals like zinc, cadmium, magnesium, etc