Threshold frequency, work function and the photoelectric equation
As described above, the threshold frequency is the minimum frequency of light required to emit photoelectrons, and this varies depending on the type of metal.
The work function of a metal is the minimum energy required for electrons to be emitted from the surface of a metal, and it is denoted by Φ.
The photoelectric equation shows the relationship between the work function, the frequency of light (shone onto the metal) and the maximum kinetic energy of the emitted photoelectrons.
Where E is the photon energy, Φ is the work function and Ek(max) is the maximum kinetic energy.