Photoelectric Effect Simulator
Classroom worksheet · Interactive simulation: https://lkforge.com/tools/physics/photoelectric-effect/
Name: Date:
Learning objectives
- Relate photon energy to frequency.
- Explain the threshold frequency and work function.
- Show why the effect supports the particle model of light.
Variables to change
- Light frequency (color)
- Light intensity
- Metal (work function)
Procedure
- Shine low-frequency (red) light on the metal and watch for emitted electrons.
- Increase the frequency toward blue/UV until electrons are emitted.
- Increase the intensity below the threshold frequency and observe.
- Above threshold, increase intensity and note the electron count and energy.
Observations
Record whether electrons are emitted versus frequency and intensity, and their maximum kinetic energy.
Questions
- Write the energy of a photon.
- What is the threshold frequency?
- Below the threshold, does raising the intensity eject electrons?
- Above threshold, what does raising intensity change?
- Write the photoelectric equation for maximum electron energy.
Answer key (instructors)
- 1. E = h·f, where h is Planck’s constant.
- 2. The minimum frequency whose photon energy equals the work function; below it, no electrons are emitted regardless of intensity.
- 3. No — intensity adds more photons but each is still too weak; frequency, not brightness, sets the energy per photon.
- 4. It ejects more electrons per second, but not their maximum kinetic energy.
- 5. KEmax = h·f − φ, where φ is the work function.
Light delivers energy in photons of energy hf. Electrons escape only when a single photon carries at least the metal’s work function, so there is a threshold frequency independent of intensity — direct evidence for the particle nature of light (KEmax = hf − φ).