Photoelectric Effect

This simulation demonstrates the photoelectric effect. Students set the frequency of the light, its intensity and the metal, choosing from caesium, sodium, zinc, copper and platinum. Photons strike the surface and electrons are released only when the photon energy hf exceeds the work function. Readouts show photon energy, threshold frequency, maximum kinetic energy and whether electrons are emitted. It is a clear way to show why brighter light does not free electrons below the threshold, and why the wave model alone cannot explain the effect.

• Set Metal to Zinc and raise Light frequency until electrons first appear, then read the Threshold f0.
• Keep the frequency below threshold and raise Intensity to 10 to see that still no electrons are emitted.
• Above threshold, double Intensity and note that more electrons appear but KE max stays the same.
• Switch Metal to Caesium and compare its threshold frequency with platinum.
• Raise the frequency and watch KE max = hf - phi increase step by step.

1. 1Explain why electrons are emitted only above a threshold frequency.
2. 2Use KE max = hf - work function to calculate electron energy.
3. 3Distinguish the effect of increasing frequency from increasing intensity.
4. 4Compare threshold frequencies of different metals.

Questions teachers ask