Question

Problem 2 (25 points) Figure shows Young's double-slit experiment with coherent light source wavelength of the light λ is 500 nm, the slit separation d is 025 mm and the slit-screen separi on 50 cm. Assume that θ is small enough to use the approximation sin θ tan θ (a) (15 points) Let's assume that there is a constant phase offset π (1800) between the lights after thesíts 1 and s2. What is the distance y on the screen between the first bright fringe (point P) and the middle of the screen? (bright (dark) fringe means where full constructive (destructive) interference occurs) (b) (10 points) Continued from (a). Now we add a transparent plastic plate (index of refraction n -1.5 an thickness L 500 nm) in front of one of the slits. Does the point P still remain as bright fringe or becon dark fringe? Explain your answer

Answer 1