Explain why, for the photoelectric effect, the existence of a threshold frequency and a very short emission time provide evidence for the particulate nature of electromagnetic radiation, as opposed to a wave theory.
State and explain two relations in which the Planck constant 
is the constant of proportionality.
that is directly proportional to its frequency 
, the energy is given by the equation:
which is given as:
is the wavelength of the particle and 
