Build a quantum experiment with interchangeable apparatus, live meters and graphs. Investigate photoemission, measure stopping potential and Planck’s constant, and explore electron diffraction.
What you can investigate
- Why photoemission depends on photon frequency rather than light intensity alone
- How work function, threshold frequency, maximum kinetic energy and stopping potential are linked
- How a current–potential curve reveals stopping potential and saturation current
- How stopping-potential data can be used to estimate the Planck constant
- How electron momentum and screen distance affect graphite diffraction rings
Try these investigations
- Change wavelength and intensity to compare electron energy with emission rate.
- Compare photon energy, work function and the spread of photoelectron energies.
- Reverse the collector polarity and observe electrons accelerate, slow or turn back.
- Find the stopping potential from the photocurrent and explain what is stopped.
- Record stopping voltages at several frequencies and fit a graph to estimate Planck's constant.
- Measure graphite diffraction rings while varying accelerating voltage and screen distance.
Revision and practice