Refraction and total internal reflection
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What this model shows
The paper, glass blocks, angle scale, ray box and light pipe are simulated, and the rays are drawn exactly, for a refractive index of 1.50. The scale is read to the nearest degree, as you would read a real one, so sin i ÷ sin r comes out at 1.51 to 1.52 and the critical angle, 41.8°, is read as 42°. The angles 20°, 40°, 50° and 60° are the model’s settings.
A real ray box gives a beam about a millimetre wide that spreads out a little, and real readings are often a degree or two out. The brightness of the reflected ray follows how much light a real glass surface reflects, but it is drawn brighter so that you can see it. The ray that leaves the curved side of the semicircular block after a reflection inside is not drawn.
A light pipe is a model of an optical fibre: a real fibre is about a tenth of a millimetre thick, so the light inside it is reflected thousands of times in every metre.
With reduced motion each step happens at once: the rays, the readings and the parts on the bench appear straight away as they are at the end of the step.
Select equipment to read its description in the card.