Laboratory work. Splitting light into a spectrum with a glass prism
You need: a light source (projector or torch), a thin slit in black paper, a glass prism (or a triangular plastic container filled with water), a white screen (wall or paper). Darken the room, direct the beam through the narrow slit onto the prism and slowly turn the prism to obtain a sharp spectrum on the screen: red, orange, yellow, green, light blue, blue, violet. Red is at one edge, and violet, which deviates most, at the other. Measure the width of the spectrum on the screen with a ruler. Repeat with another prism (or with the prism farther from the screen) and compare widths: the farther the screen from the prism, the wider the spectrum; the glass type and prism angle also matter. Then isolate one colour with a card and pass it through a second prism: it does not split further — a pure colour. Extra: a spectrum can also be seen on a shiny CD or in a soap bubble.
Laboratory work (in groups): produce the spectrum and record the colour order and the width. Safety: never look at the Sun directly, cast sunlight through the prism only onto a wall; do not use a laser pointer; prism edges are sharp, be careful; a projector gets hot — do not touch it.