Chapter 36, Problem 40AP

Why is the following situation impossible? A piece of transparent material having an index of refraction n = 1.50 is cut into the shape of a wedge as shown in Figure P36.40. Both the top and bottom surfaces of the wedge are in contact with air. Monochromatic light of wavelength λ = 632.8 nm is normally incident from above, and the wedge is viewed from above. Let h = 1.00 mm represent the height of the wedge and ℓ = 0.500 m its length. A thin-film interference pattern appears in the wedge due to reflection from the top and bottom surfaces. You have been given the task of counting the number of bright fringes that appear in the entire length ℓ of the wedge. You find this task tedious, and your concentration is broken by a noisy distraction after accurately counting 5 000 bright fringes.

Figure P36.40