Turn on the laser by touching the metal plate.
Red wheel: Adjust the light source to maximum brightness.
Green wheel: Turn the lattice until you can see the spectrum on the screen.
Blue wheel: Turn the wheel until you get the narrowest aperture possible.
How does the spectrum changes with
- the intensity of the light?
- the position of the lattice?
- the width of the aperture?
Also try
Make the aperture as wide as possible. Notice the white area in the spectrum.
What has happen to the green colour?
Make the aperture narrower. What happens when the white area in the middle disappear?
Fun facts
We use a lattice instead of a glass prism. The lattice is a piece of glass with several thin lines. This lattice makes a brighter spectrum than an ordinary prism.
With a broad aperture you can see two edge spectrum, one red/yellow and one light-blue/violet. When the aperture width is reduced, the yellow and the blue light meet to make green. We can then see a continuous spectrum from red to deep blue (violet).