Refraction and total internal reflection sim
The beam enters the curved side along a radius, so it meets that surface square on and does not bend.
Refraction and total internal reflection · covers the GCSE, IGCSE, O-Level topic
What the sim shows
The beam enters the curved side along a radius, so it meets that surface square on and does not bend. At the flat side it meets the normal at angle i. Light going from glass into air speeds up and bends away from the normal: n = sin r ÷ sin i, with n = 1.5 for this glass. Some light is always reflected back too, more as i grows. At the critical angle c, where sin c = 1 ÷ n, c = 41.8°, the ray leaves along the flat side (r = 90°). For any bigger angle no light can leave: it is all reflected back into the glass, total internal reflection, as in optical fibres and prism periscopes. The rays are drawn as bright as the share of light they carry.
- Light rays, as bright as the light they carry
- Right: Snell's law worked through
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