Practice question

**TIR application** requires n₁>n₂ and θ₁>C. Critical angle formula derived from Snell's law with θ₂=90°, n₁ sinC = n₂ sin90° = n₂, so sinC = n₂/n₁. For glass-air sinC=1/1.52, C≈41°, for water-air 48.6°, determining cutoff for transmission. The mirage effect on hot roads results from total internal reflection. Hot air near the ground has a lower refractive index than cooler air above, causing light from the sky to bend upward when the angle of incidence exceeds the critical angle, creating an illusion of water. Substituting values gives Total internal reflection, which matches expected image position and magnification from mirror/lens formula 1/f = 1/v - 1/u