Slides in this set
The photoelectric effect was discovered by Hienrich Hertz
He was studying lights effects on different metals as back
up to some previous work of Becquerel in 1837.
He discovered that when you shine visible light on a alkali
metals it can emit electrons.
This was also shown to work with
other metals in UV electromagnetic
The First Theory
Theory that was proposed to explain this effect was that
as light hit the material it gave energy to the electrons on
the surface of the metal.
These electrons then have enough energy to escape the
surface of the metal causing a current.
According to classical mechanics
if you shined a high intensity,
low energy beam of light,
it would emit the same amount
of photoelectrons as a
low intensity, high energy beam.…read more
However this theory had a
Electrons were only were
only emitted after a certain
frequency/energy light was
shined on to it.
Before that frequency there
was no emission, however
high the intensity of the
light. This went against all
classical mechanics…read more
This was discussed for many
years with no resolve.
In 1905 Einstein solve this
Using the work of Max Plank
into the photon ( a packet of
light) he described the effect
in the equation hf=+ Ek
Einstein went on to win his
Nobel prize in this. Not
The equation was very simple but explain perfectly
the effect and was made up of three parts
The energy of each photon hitting the surface of the
metal. It calculated from Planks Law, E=hf, where
E the energy of the photon, J
h is planks constant 6.6x10-34 ,m2kg s-1
f is the frequency of the light…read more