A red filter is placed between the prism and the screen.
(ii) What would you now see on the screen?
Nothing - no light would get through to the screen ![](../../../graphics/symbols/nuclides/ticksmall.png)
(iii) Explain how the red filter causes the change.
A red filter would absorb all of the blue light. ![](../../../graphics/symbols/nuclides/ticksmall.png)