This simulation shows a marching band model for refraction. We're looking at an overhead view of five rows of the marching band. When the band moves from one surface (say, a parking lot) to a different surface (say, a grassy field), the speed of the marchers can change. Associated with that change in speed is, often, a change in direction - this happens if different marchers in a particular row reach the second surface at different times.
This is an analog of the behavior of light when it travels from one medium to another. The index of refraction of the media can be set with the sliders - the larger the index of refraction, the slower the marchers (the light) travels in that medium. The angle of incidence, measured from the normal (perpendicular to the interface), can also be set with a slider.
Simulation written by Andrew Duffy, and first posted on 2-13-2018.
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