🔭 Optics Physics Game

Optics Puzzle — Free Online Ray Tracing & Light Physics Game

Optics Puzzle uses a full recursive ray-tracing engine — every reflection, refraction and lens bending is computed using real physics equations. Place mirrors and prisms to navigate laser beams to their targets across 8 levels.

The physics behind the game

Law of reflection

θᵣ = θᵢ

The angle of reflection equals the angle of incidence, measured from the normal to the surface. This governs every mirror interaction in the game.

Snell's law (refraction)

n₁·sinθ₁ = n₂·sinθ₂

When light crosses a boundary between media of different refractive indices, its direction changes. Glass has n ≈ 1.5, so light bends toward the normal on entry and away on exit.

Thin lens equation

1/f = 1/v − 1/u

A convex lens brings parallel rays to a focal point at distance f. A concave lens diverges them. The game models this by bending each ray toward or away from the focal point on intersection.

Total internal reflection

θ_c = arcsin(n₂/n₁)

When light tries to exit a denser medium at an angle beyond the critical angle, it reflects completely — this is the principle behind optical fibres.

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Reflection, Refraction, and Snell's Law

Law of Reflection: θ_i = θ_r

The angle of incidence equals the angle of reflection, both measured from the normal to the surface. The incident ray, reflected ray, and normal are coplanar. This applies to all waves: light, sound, radar. A concave parabolic mirror focuses all parallel rays to a single focal point f = R/2 (R = radius of curvature) — the basis of telescope mirrors, satellite dishes, and car headlight reflectors.

Snell's Law: n₁ sinθ₁ = n₂ sinθ₂

Refraction at a boundary between media of refractive indices n₁ and n₂. n = c/v (speed of light in vacuum / speed in medium). Air ≈ 1.000, water = 1.333, crown glass = 1.52, diamond = 2.42. Light bends toward normal entering denser medium (n₂ > n₁, θ₂ < θ₁). Derivation: one side of the wavefront slows first, rotating the wavefront direction. This bending causes apparent shallowing of pools, bent straws, and mirages.

Total Internal Reflection and Critical Angle

When going from dense to less dense (n₁ > n₂), at angle above θ_c = arcsin(n₂/n₁), all light reflects — no refraction. Glass (n=1.52) to air: θ_c = 41.1°. Diamond: θ_c = 24.4° — small critical angle means most light undergoes multiple total internal reflections, creating extraordinary brilliance. Optical fibres: glass core (n ≈ 1.5) in cladding (n ≈ 1.46). TIR keeps light trapped, enabling terabit/s data transmission through fibres thinner than a hair.

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