Waves & Optics — Interactive Lab

Reflection & Refraction

Fire a ray of light at the boundary between two media. Watch it reflect and refract, and push the angle past the critical angle to trigger total internal reflection.

Controls

Angle of incidence 40°

Index n₁ (upper medium) 1.00

Index n₂ (lower medium) 1.50

Angle of reflection40.0°

Angle of refraction25.4°

Critical angle—

Light bends toward the normal as it enters the denser medium.

Angles are measured from the normal (the dashed perpendicular). When n₁ > n₂, raise the angle past the critical angle to see all of the light reflect back — total internal reflection.