Light bends at each interface per Snell's law: n₁ sinθ₁ = n₂ sinθ₂.
A converging lens bends every parallel ray to meet at one focal
point; a prism bends each wavelength by a slightly different
amount, spreading white light into a spectrum (dispersion).
- Mode — switch between a converging lens and a triangular prism.
- Angle of incidence — the angle the incoming ray makes with the surface normal.
- Focal length — where the lens converges parallel rays (lens mode only).
- Material (n₂) — the refractive index of the glass/water/diamond the ray enters; higher n₂ bends light more and lowers the critical angle for total internal reflection.
- Wavelength — sets the ray colour and slightly changes the index (dispersion), same as a prism splitting white light into a rainbow.
Real-world link: total internal reflection above the critical angle is exactly how
light stays trapped inside a fiber-optic cable, carrying data over long distances with almost no loss.