Triangular Prisms 1
Physics: Cambridge International GCSE Supplement, topic 3.4.2
Triangular Prisms
A triangular prism can also be used to create a spectrum.
Different frequencies travel at different speeds
- The incident ray of white light enters the prism.
- The different frequencies of the colours travel at different speeds through the prism.
Different colours are refracted by different amounts
- The different colours (frequencies) are refracted by a different amount when they enter the prism.
- Therefore, the emergent ray (coming out of the medium) is red on one side and violet on the other.
Different speeds of light
- Red light’s speed changes the least when entering the prism, so its direction changes the least.
- Violet light’s speed changes the most (slows down) in the prism, so its direction changes the most.
Test yourself on Triangular Prisms 1
Which colour light changes direction the least when passing through a prism?
What is the name given to a ray of light entering a prism?