80. Wave Particle Duality

The Ripple Tank is useful to remind the students of wave interference. You might also wish to use the Acoustic Interference demonstration with the ultrasonic transducers. With this setup, you can show that covering one of the two sources will increase the signal to the detector in the case of destructive interference, a key property of waves.

Light has wave properties: show interference with laser shining through slits (See Interference and Diffraction).
Light has particle properties: show the Photoelectric Effect.
Electrons have wave properties: show Electron Diffraction.