For this air-to-material model, Snell's law is n 1 sin(theta 1) = n 2 sin(theta 2). A higher second index gives a smaller transmitted angle for the same incident angle. The ray therefore moves closer to the normal. These approximate indices represent one visible-light comparison; real indices vary with wavelength and conditions.
Light, sound and electricity · Discover & try
Why does light bend at a boundary?
Reading level 4 of 5 · FluentChange
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refraction
A change in light direction across a material boundary.
refractive index
A ratio describing light speed in a material.
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Flat air-to-material interface using approximate visible-light indices; reflected light is omitted.
What to look for
- The normal stays fixed
- Glass and water bend differently
- Straight entry has no sideways bend
Explain what you noticed
A ray enters glass from air at 50° from the normal. How does its transmitted angle compare?
Keep this idea: Compare direction with the normal while holding the incoming angle fixed.
Follow the sources
- OpenStax / Rice University — The Law of Refraction
- NASA / Smithsonian Chandra — Somewhere Over the Rainbow
Source material checked 2026-10-28. Explanations and activities by Nepedia. Source links do not imply endorsement.
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