Practice question

**Refraction at plane surface** changes direction due to speed change v = c/n, n = c/v. For water n=1.33 to air, n₁>n₂, ray bends away, if θ₁ > C, sinθ₂>1 impossible, TIR occurs. Snell's law quantitative prediction of θ₂ from θ₁ and indices. When a convex lens is in a medium with a higher refractive index than the lens material, the refractive index difference reverses (medium > lens), causing the lens to diverge light instead of converging it. This occurs because the rays bend away from the normal at the interfaces. Substituting values gives It behaves as a diverging lens, which matches expected image position