Electromagnetic radiation of a single constant frequency is incident on a metal surface. This causes an electron to be emitted. Explain why the maximum kinetic energy of the electron is independent of the intensity of the incident radiation.
Ultraviolet radiation of wavelength 
is incident on the surface of a sheet of zinc. The maximum kinetic energy of the emitted electrons is 
. Determine, in 
:
the energy of a photon of the ultraviolet radiation
the work function energy of the surface of the zinc.
.
.
