Fiber Optic Cable Simulator (2D)

This 2D side-view simulator sends a light ray zig-zagging down the core of an optical fiber and works out, at every bounce, whether it reflects perfectly or leaks — using the real Snell's-law critical angle θc = arcsin(n₂/n₁). Drag the incidence angle slider to change how steeply the ray strikes the core/cladding boundary, and adjust the core index n₁ and cladding index n₂ to see the critical angle shift live: keep the incidence angle above θc and the ray travels the whole core by total internal reflection with no loss, but drop it below θc — or narrow the index gap between core and cladding — and the ray punches through into the cladding, exactly the mechanism that caps how sharply a real fiber optic cable can be bent before its signal degrades.