A beam of diameter ‘d’ is incident on a glass hemisphere as shown. If the radius of curvature of the hemisphere is very large in comparison to d, then the diameter of the beam at the base of the hemisphere will be :-

Question

G1 Physics · Accepted Answer

Derived solution: Step 1: For paraxial refraction at a spherical surface use n₂/v - n₁/u = (n₂ - n₁)/R, applying the Cartesian sign convention at each surface. Step 2: Substitute the values given in the question and apply the geometry/sign convention shown. Step 3: On simplification the result is 2d/3. Therefore the correct option is D.