State three pieces of evidence provided by the photoelectric effect for a particulate nature of electromagnetic radiation.
The work function energies of some metals are shown in the table below.
Each metal is irradiated with electromagnetic radiation of wavelength 
.
Calculate the energy, in 
, of a photon of electromagnetic radiation of wavelength .
Determine which metals will give rise to the emission of photoelectrons. Explain your answer.
Photons of wavelength are incident normally on a metal surface at a rate of 
. All the photons are absorbed in the surface and no photoelectrons are emitted. Calculate the force exerted on the metal surface by the incident photons.
.
.
