Quantum
Behavior
The
Quantum Universe
The Photoelectric
Effect
Other evidence that photons exchange energy in packets/quanta (E =
hf) (This page)
weblinks
A set of notes in Word format containing all the content from the four webpages (above) on quantum behaviour is available here
Other evidence that photons exchange energy in packets/quanta (E =
hf)
The electrons
within an atom can only have a certain number of different possible
energies, These can be shown in
an energy level diagram |
The electron
usually sits at the lowest level |
It needs a precise
amount of energy to rise up to any of the higher levels |
When it moves back
down from the higher energy level to the original level then the
same precise amount of energy is released |
This energy is
released as a photon of frequency f |
The relationship
between the energy of the photon and its frequency is expressed by
ΔE=hf where h is Plank's constant |
The energy levels
are irregularly spaced and so photons of different energies are
released |
If you have a gas
discharge tube, the electrons inside it are constantly being excited
up to higher energy levels as well as moving back down, releasing
photons of specific energies |
If you view the
light emitted from a gas discharge tube through a diffraction
grating then you will observe a line spectra |
Each of these
different coloured lines relates to a specific change in energy
levels and thus a specific frequency of photon |
Because different
elements have different (and unique) sets of energy levels then they
have unique spectra |
| Hydrogen |  |
Krypton |  |
| Helium |  |
Mercury |
 |