Photoelectric Effect: free physics simulation
Shine light on a metal and knock out electrons. See why colour, not brightness, decides whether it works.
▶ Open the simulationFree, no sign-up. Works on phones, tablets and laptops.
The science
Light knocks electrons out of a metal only if each photon carries more energy than the metal’s work function. Photon energy depends on colour (frequency), not brightness, so bright red light can fail where dim ultraviolet succeeds. Brighter light frees more electrons but not faster ones. Einstein’s explanation of this in 1905 showed that light comes in packets called photons.
KEmax = hf − φ (E = 1240 / λ eV, λ in nm)
Things to try
- Shine bright red light on sodium and see that no electrons escape.
- Switch to violet light and watch electrons jump out.
- Make the voltage negative until the current just stops: that is the stopping voltage.
Topics covered
photon quantum work function einstein stopping voltage threshold frequency planck light electrons
How to use it
Open the simulation, then change the experiment live with the sliders, checkboxes and buttons in the side panel. Drag objects on screen where it makes sense, and use Pause, Step, Speed and Reset in the bottom bar to study every moment.
Frequently asked questions
What does the Photoelectric Effect simulation show?
Light knocks electrons out of a metal only if each photon carries more energy than the metal’s work function. Photon energy depends on colour (frequency), not brightness, so bright red light can fail where dim ultraviolet succeeds. Brighter light frees more electrons but not faster ones. Einstein’s explanation of this in 1905 showed that light comes in packets called photons.
What is the key equation?
KEmax = hf − φ (E = 1240 / λ eV, λ in nm)
Is the Photoelectric Effect simulation free?
Yes. It runs free in any web browser on phones, tablets and laptops, with no sign-up or download.
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