Photoelectric effect · light is lumps simulation

When light ejects electrons from a metal, what sets their energy — the brightness of the light or its colour? And what does the answer say light is made of?

▶ Run the simulationSee the measured result

Units: J·s (Planck's constant, exact in the 2019 SI; Millikan's 1916 slope measurement gave 6.57e-34)

How the lab tests it

For six real metals (Cs, Na, Ca, Zn, Cu, Pt) generate the stopping-voltage data above each threshold and least-squares fit Einstein's photoelectric line V_stop = (h/e)ν − φ, then read off the slope, the threshold ν₀, and the work function from the intercept.

What it checks

the slope h/e is UNIVERSAL — identical across all six metals (the spread is ≈0), because the energy of a light quantum E = hν is a property of light, not of the metal; Planck's constant backs out as h = slope·e = 6.626×10⁻³⁴ J·s (Millikan's 1916 measurement); each work function φ is recovered from the line's intercept; and below the threshold frequency ν₀ = φ/h NO electrons escape at ANY intensity — the quantum signature classical wave theory cannot explain (a brighter wave should always free electrons). Einstein's 1905 Nobel result, the one that made the photon real