Задача 40469.

Find the smallest radius of a circular hole in the diaphragm such that, when illuminated by a plane monochromatic wave, a dark spot is observed on the screen in the center of the diffraction pattern. It is known that the radius of the third Fresnel zone with this arrangement of the diaphragm and screen is 2 mm.

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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