10. The monochromatic light is normally incident alternately on the two plates are made from the same material, a thickness d1 = 4 mm, the other - d2 = 8,5 mm. Neglecting secondary reflections determine the absorption coefficient α of the material if the first plate passes η1 = 0,7 light flux, the second - η2 = 0,52.

Detailed solution. Decorated in Microsoft Word 2003. (Target decided to use formula editor)