Ripple Tank
Overview: Light acts as both a wave and a particle. Water waves can be used to visibly demonstrate the wave properties of light
Supplies: Ripple tank, wave motor, post for wave motor, different wave devices, different interference devices, white paper or white screen, distilled water
Objectives: Using various wave generators, wave speeds and waver interference devices, show how water (and also light) behaves in wave motion
Setup:
- Fill the tank with water so the paddles touch the surface of the water
- Plug in and turn on the light overhead
- Choose a wave generator device and attach it to the motor arm
- Turn on wave motor
- Place white paper, or white screen underneath the tank to act as a screen
How to run the demo:
- Change the frequency of the oscillating pattern and whether the paddles are in phase or out of phase.
- Having the light strobe or be constant will make the pattern appear moving or stationary.
- Place wave blocking devices in the water and see how that changes the wave patterns
What’s Happening?
The ripple tank demonstrates the wave behavior of light. Spherical waves emanate from both paddles and expand outwards, and where they overlap you will have constructive or destructive interference. This is being demonstrated with water, but the same behavior can be observed with light. This can illustrate refraction and reflection, but also diffraction and interference.
Learn more: (external links)
PhET Interactive wave simulation: https://phet.colorado.edu/en/simulation/wave-interference
Video of a ripple tank (the first 2minutes are setup of a similar system, skip to 2:10 to see it in action)