15.5: The Photoelectric Effect

Describe an interaction between photons and matter using the photoelectric effect.

• 15.5.A.1 The photoelectric effect is the emission of electrons when electromagnetic radiation is incident upon a material.

• 15.5.A.2 The emission of electrons via the photoelectric effect requires a minimum frequency of incident light, called the threshold frequency.

  • 15.5.A.2.i Light that is incident on a material at the threshold frequency or higher will induce electron emission, regardless of the number of photons that strike the material.

  • 15.5.A.2.ii The energy of the emitted electrons is not dependent on the number of photons that are incident upon the material, which provides evidence that light is a collection of discrete quantized energy packets called photons.

• 15.5.A.3 The maximum kinetic energy of an emitted electron is related to the frequency of the incident light and the work function of the material.

  • 15.5.A.3.i The work function of a material is the minimum energy required to emit an electron from atoms within the material.

  • 15.5.A.3.ii The maximum kinetic energy of an emitted electron is given by the equation

• 15.5.A.4 Stopping potential is the minimum applied electric potential difference that stops the flow of electrons.

  • 15.5.A.4.i For applied potential differences less than the stopping potential, an electron is able to be emitted.

  • 15.5.A.4.ii The stopping potential is proportional to the maximum kinetic energy of ejected electrons.