Experiments with Colours

Aims:

· Put the arrangement (sketched below) together on the guide rail. Try to pull the different colours in the spectrum apart by turning the prism. Put a thin piece of cardboard or a pencil in the way of the red light. Converge the rest of the light on the white screen by using a convex lens. What can you see on the white screen?

· Try to fade out any other colour (colours) and do the same. (Result?)

· Take the second lens away and try to get a good spectrum on the white screen. Hold differently coloured objects one after the other so that the spectrum hits them. What can you see?

· Draw lines on a sheet of paper with coloured chalk and look at them in the light of the spectrum.

· Hold differently coloured glasses into the spectrum. (Result?)

· Now put one differently coloured glass after the other at the place shown left.

Look at the spectrum of the light that went through the coloured glass. What can you see?

· Light all sorts of coloured things with coloured light by putting coloured glass in front of the lamp. (Take away prism, lens and gap first!) Try to explain what you see!

· Create red, green and blue light by putting coloured glasses in front of three lamps. Focus the three beams of light to a white screen, so that they overlap each other. What can you see? (Why?)

List of Materials:

· one lamp (with current source)

· two pieces of cardboard (with holders)

· one lens (f = 10 cm) (with holder)

· one prism (with holder)

· one guide rail

· one white screen (with holder)

· one lens (f = 5 cm) (with holder)

· one thin piece of cardboard or one pencil

· coloured chalk and a piece of paper

· coloured glass (red, green and blue)