Practice question

**Snell's law** n₁ sinθ₁ = n₂ sinθ₂ describes refraction at plane interface, n refractive index, θ angle with normal. When light goes from denser n=1.52 glass to rarer air n=1, sinθ₂ = (n₁/n₂) sinθ₁ > sinθ₁, bending away from normal, enabling total internal reflection beyond critical angle. Shift = t ( 1 - (1/n) ) . t = 7.6 cm , n = 1.52 . Shift = 7.6 ( 1 - (1/1.52) ) = 7.6 ( 1 - 0.658 ) = 7.6 × 0.342 ≈ 2.6 cm . Substituting values gives 2.6 cm, which matches expected image position and magnification from mirror/lens formula 1/f =