Задача 40582.

The light guide is a long thin thread made of a homogeneous transparent material with a refractive index n= 1.2. Near one of the ends there is a light source S, the other end is placed at a distance of 50 cm from the screen. Find the diameter d of the light spot on the screen.

Detailed solution with a brief record of the conditions, formulas and laws used in the solution, derivation of the calculation formula and answer.
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