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. The focal point of a convex mirror is virtual and behind the mirror because reflected rays diverge and appear to originate from this point when traced backward. This indicates the mirror’s diverging nature, ensuring all images are virtual, erect, and diminished. Substituting values gives It is the point where diverging rays appear to originate, which matches expected image position and magnification from