Final answer:
The photoelectric effect is the ejection of electrons from a material due to incident light above a certain threshold frequency, which can create an electric current and is used in devices like light meters and solar cells.
Step-by-step explanation:
The photoelectric effect is a phenomenon where light incident on certain materials can cause the ejection of electrons from those materials. Key to this effect is the frequency of the incoming light. Light with a frequency below a certain threshold frequency will not eject electrons regardless of its intensity, while light with a frequency above that threshold can eject electrons even if its intensity is low. When electrons are ejected, they can create an electric current, which is a flow of electric charge. This process is harnessed in applications such as light meters and solar cells, which convert light into electricity.