A point source S is placed at the bottom of a transparent block of height 10 mm and refractive index 2.72. It is immersed in a lower refractive index liquid as shown in the figure. It is found that the light emerging from the block to the liquid forms a circular bright spot of diameter 11.54 mm on the top of the block. The refractive index of the liquid is:-

Question

G1 Physics · Accepted Answer

Derived solution: Step 1: Use Snell’s law at each plane interface. For paraxial viewing through a plane surface, apparent depth = real depth × n(observer)/n(object medium). Step 2: Substitute the values given in the question and apply the geometry/sign convention shown. Step 3: On simplification the result is 1.36. Therefore the correct option is C.