Practice question

**Refractive index** n = c/v, water 1.33 means light 1.33 times slower than vacuum. Passing from water to air at 49°, n₁ sinθ₁ =1.33×sin49°≈1.33×0.755=1.004>1, so sinθ₂>1 impossible, total internal reflection occurs, no refraction. The deviation in a prism occurs because light refracts at both the entry and exit faces, bending toward the normal when entering (denser medium) and away from the normal when exiting (rarer medium). The prism’s geometry and refractive index determine the total deviation angle. Substituting values gives Refraction at the prism’s interfaces, which matches expected image position and magnification from mirror/lens formula 1/f = 1/v - 1/u (lens) or 1/f = 1/v