What causes dispersion?
The only thing we saw in this chapter that causes it is refraction; Because blue light and red light travel at different speeds in transparent materials, those colors are bent by different amounts when there is refraction; In usual transparent materials blue light moves slower than red light, because its frequency matches better the electrons’ motions frequencies, so blue light is bent more. • Rainbows: By a combination of refraction and reflection, sunlight is bent by small droplets of water suspended in the atmosphere; Because of dispersion, light of different colors is bent by different angles; As a result, we see blue light coming from droplets that are lower than the ones from which we get red light.
