Describe light as a stream of photons with a particular energy as determined by the frequency. The energy of light is directly proportional to the frequency of the light meaning that higher frequency translates into greater energy.
Describe how, when light is shone onto a metal, the energy from the light causes the electrons within the atoms of the metal to move around. This produces a current in the metal. However, only light of a sufficient frequency will produce a current within the metal.
Describe how light with a sufficient energy will result in the emission of an electron from the metal object. This occurs due to the transfer of energy from the photons to the electrons, which gain enough energy to essentially break away from the metal atoms. Photons with higher energy result in a greater number of electrons emitted. You can also describe the amount of energy of an individual emitted electron as the energy of the photon minus the energy required to remove the electron.
Identify the frequency and energy of light as the main factor in the photoelectric effect. Light with an insufficient frequency will not emit an electron despite an increasing intensity. For example, increasing the intensity of red light shone on a metal will not result in the emission of an electron because red light does not have a sufficient frequency.