Photoelectric Effect Simulation
This simulation lets you shine light of adjustable frequency and intensity onto a chosen material and observe whether electrons are ejected, and with what kinetic energy, illustrating Einstein's 1905 explanation of the photoelectric effect.
Interactive simulation
The physics behind this simulation
Einstein's 1905 explanation (for which he received the 1921 Nobel Prize in Physics) treats light as a stream of discrete photons, each carrying energy E = hf, where h is Planck's constant and f is the light's frequency. When a photon strikes the material's surface, it can transfer its entire energy to a single bound electron. If that energy exceeds the material's work function Φ — the minimum energy needed to free an electron from the material's surface — the electron escapes with leftover kinetic energy:
The stopping voltage V_stop is the reverse voltage needed to stop even the fastest ejected electrons from reaching a collector, and is related to the maximum kinetic energy by eV_stop = KE_max, making it directly and easily measurable in the lab — historically the primary experimental method used to confirm Einstein's equation and measure Planck's constant independently of blackbody radiation experiments.
Sources
- Einstein, A. (1905). "Über einen die Erzeugung und Verwandlung des Lichtes betreffenden heuristischen Gesichtspunkt." Annalen der Physik, 17(6), 132–148.
- Millikan, R.A. (1916). "A Direct Photoelectric Determination of Planck's h." Physical Review, 7(3), 355–388 — the definitive experimental confirmation.