Solving a problem in physics section 2 point 40 optics

Solving a problem in physics section 2 point 40 optics

40. Installation for observation of Newton´s rings is illuminated by monochromatic light with a wavelength λ = 0,55mkm normally incident. Determine the thickness dk of the air gap formed by a plane-parallel plate and contacting it with a plano-convex lens at the location where the reflected light is observed fourth dark ring.

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