Photons and energy
The energy of a photon depends on its frequency.
Whether or not photoemission takes place depends on:
- the energy of the photon
- the type of metal being tested
The energy of a photon is directly proportional to its frequency. This gives rise to this equation:
\(E=hf\)
\(E\) is the energy of the photon
\(h\) is Planck's constantMathematical constant that links the frequency of a wave or particle with its total energy. It's value is 6.63 x 10-34 J s, \(6.63\times 10^{-34}Js\)
\(f\) is the frequency of the radiation
Threshold frequency and work function
The minimum frequency required to cause photoemission is called the threshold frequency, \(f_{o}\)
The minimum energy required to remove an electron from a metal is called the work function, \(W\)
These are related by this equation:
\(W=hf_{o}\)
Different metals have different work functions. This means it is easier to remove electrons from some metals than others.
In turn, this means that the minimum frequency of photon needed to remove an electron from one metal can be lower than for another metal.