OUTCOME
By the end of this lesson you will be able to describe and explain dispersion and how it is a result of the refractive index of different colours. You will be able to link Dispersion to our understanding of the speed of light in a medium.
When light travels through a medium it interacts with the matter and thus slows down. The proportion to which it slows down is equivalent to its refractive index
Dispersion occurs when light reaches it critical angle in a medium. The critical angle for each frequency (colour) is slightly different enabling the colours to be seen as each reaches its own critical point.
LEARNING TASKS
Explain
Why does TIR only occur from more dense to less dense mediums?
Evaluate
Ex 10.3 Qs 5-13
PDQs 1.15, 1.16