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. When the object is at the focal point of a concave mirror, the reflected rays become parallel and do not converge to a point. This results in the image being formed at infinity, meaning no distinct image forms at a finite distance. Substituting values gives Parallel reflected rays forming image at infinity, which matches expected image position and magnification from mirror/lens formula 1/f = 1/v - 1/u (lens) or 1/f = 1/v