ANewtons ring apparatus consists of a plano-convex glass

Chapter , Problem 31

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ANewtons ring apparatus consists of a plano-convex glass lens that has a radius of curvature and rests on a flat glass plate, as shown in Figure 33-42. The thin film is air of variable thickness. The apparatus is illuminated from above by light from a sodium lamp that has a wavelength equal to The pattern is viewed by reflected light. (a) Show that for a thickness the condition for a bright (constructive) interference ring is where (b) Show that for the radius of a fringe is related to by (c) For a radius of curvature of and a lens diameter of how many bright fringes would you see in the reflected light? (d) What would be the diameter of the sixth bright fringe? (e) If the glass used in the apparatus has an index of refraction and water replaces the air between the two pieces of glass, explain qualitatively the changes that will take place in the bright-fringe pattern.