Problem 40386.

Problem 40386.

A thin layer of a transparent substance with a refractive index n=1.3 is applied to a glass plate. The plate is illuminated by a parallel beam of monochromatic light with a wavelength of 640 nm, incident normally on the plate. What minimum thickness must the layer have in order for the reflected beam to have the lowest brightness?

Additional information:

Detailed solution with a brief record of the conditions, formulas and laws used in the solution, derivation of the calculation formula and answer.
If you have any questions regarding the solution, please write. I try to help.