Einstein's Photoelectric Equation

A photon has energy: E=hf When it interacts with an electron, part of this energy is required to release the electron from the material. This minimum energy is: work function `φ` Remaining energy becomes maximum photoelectron kinetic energy: hf = φ + K_max Therefore: K_max = hf−φ Since: φ=hf₀ we get: K_max = h(f−f₀) If stopping potential `V_s` just stops the fastest photoelectrons: **K_max=eV_s Therefore: eV_s=hf−φ**

A graph of `K_max` against `f` has: slope: **h and frequency-axis intercept: f₀**

**hf=φ+K_max K_max=h(f−f₀) K_max=eV_s**