Interesting stuff. Thanks Parson!
It is interesting to note that the modern LED light was explained by Einstein. The effect works both ways: Photons hitting a metal surface causes electrons to flow (given a path), and electrons hitting metal at the right energy level produces photons (what occurs in the LED).
From
here:
In 1905, Einstein proposed an explanation of the photoelectric effect using a concept first put forward by Max Planck that light waves consist of tiny bundles or packets of energy known as
photons or quanta.
Diagram of the maximum kinetic energy as a function of the frequency of light on zinc
The maximum
kinetic energy
of an ejected electron is given by
where is the
Planck constant and
is the frequency of the incident photon. The term
is the
work function which gives the minimum energy required to remove a delocalised electron from the surface of the metal. The work function satisfies
=
hf0
where
is the threshold frequency for the metal. The maximum
kinetic energy of an ejected electron is then
Kinetic energy is positive, so we must have
for the photoelectric effect to occur.