Year 11, University High School
Crown Refraction Pattern
This photo demonstrates two physics concepts: colour addition and light refraction. The set-up was as follows: a standard light box was placed on the bench, with red, green and blue filters over the three windows. A semicircular prism was placed in front, and the three beams of light were directed by their mirrors to shine into the flat side of the prism. As can be seen, the light beams are not affected by one another, and are refracted individually by the prism. Because the prism is curved, the pattern produced on the paper behind is curved. The three beams of light cross one another at several places, causing a colour addition in each of these regions. Where all three beams illuminate a region, it appears white. Where red and blue, it is magenta; where blue and green, it is cyan. Because of the design and arrangement of the beams, red and green are never together without the presence of blue, which would result in yellow. Areas not exposed to the light are black.