gen-explain-the-critical-angle-as-you-would-to-a-capable-student-671a

Explain the critical angle as you would to a capable student, in 3-4 sentences.

The critical angle is the specific angle of incidence in the denser medium at which light refracts along the boundary (at 90°) when moving toward a less dense medium. Beyond this angle, instead of refracting out, light undergoes total internal reflection and bounces back into the denser medium. You can calculate it using sin(θc) = n₂/n₁, where n₁ is the refractive index of the denser medium and n₂ is that of the less dense medium. This phenomenon is why fiber optic cables work and why diamonds sparkle so brilliantly.