Лаг1989 задача №22.30

The absorption coefficient of a transparent plate for a certain wavelength changes linearly from 0.8 m⁻¹ at one surface of the plate to 1.2 m⁻¹ at the other surface. When monochromatic light of a given wavelength passes through such a plate, its intensity decreases by 10. Find the thickness of this plate.

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