🌊 Refraction — how a ray bends crossing into a denser medium

A ray crosses from air into glass. It bends toward the normal, and part of it reflects back. Change the angle i and the index n and watch the bend and the split respond.

Walkthrough 1 / 4

Step 1 — the boundary, the normal and the incoming ray at angle i. Nothing has crossed yet.

Angle of incidence i 40°

Refractive index n 1.50

i = 40° → r = 25.4° · n = 1.50
denser medium → ray bends TOWARD the normal (r < i)

Animation speed 1.0×