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1. Describe the dispersion of light by a glass prism.

When light enters a different medium, the change in wavelength and speed depends slightly on the frequency of the wave. The higher the frequency, the higher the change in speed. We call this effect dispersion.

White light is made up of the seven colours of the rainbow – red, orange, yellow, green, blue, indigo, violet – listed in order of increasing frequency. You can remember them in order using the name Roy G. Biv (I have no idea who Roy is or if he’s even real, but I watched a video about him in physics in year 7). Each letter in the name stands for a colour of the rainbow.

When white light is passed through a prism, it refracts and disperses into those seven colours. The colour with the highest frequency, violet, refracts the most and the colour with the lowest frequency, red, refracts the least.

Notes submitted by Lintha and edited by Sarah.