Physics
Threshold Frequency
Quick fact
Threshold frequency is the lowest frequency of light needed to eject electrons from a material.
Why this is interesting
Did you know that shining a green laser on a metal might not make it glow, but a bright red one could? It all depends on the light’s frequency.
Read the full explanation
Understanding Threshold Frequency
Imagine light as tiny packets called photons. Each photon carries energy based on its frequency. When light hits a metal, it can knock out electrons if the photons have enough energy—this minimum required frequency is called threshold frequency.
A deeper explanation
Threshold frequency is determined by the work function of the material, which is the energy needed to free an electron from its atomic bonds. If the photon’s energy (E = hf) is equal to or greater than the work function, electrons are ejected. This principle explains how solar cells and photodetectors convert light into electricity.