Midterm Exam 2 Wave optics, Diffraction Patterns, Polarization, Special Relativi

Question

Midterm Exam 2 Wave optics, Diffraction Patterns, Polarization, Special Relativity . You have 70 minutes to complete the exam. .The exam consists of 7 open questions. · The best 5 answers for questions 1-6 will be taken into account; question #7 is mandatory. Equations are on pages 5-7 Total number of points: 70. . 1. A Young's interference experiment, whose schematic is shown in the figure below, is performed with blue-green laser light. The separation between the slits is 0.480 mm, and the screen is located 3.12 m from the slits. The first bright fringe is located 3.05 mm from the center of the interference pattern. What is the wavelength of the laser light? (10 points) Hint: Use the approximation sin ~ tan for small angles 5°. L. Viewing screen

Explanation / Answer

path difference between the waves arriving = d*sintheta

for the bright fringe at p , path difference = m*lambda

d*sintheta = m*lambda

for small angle sintheta = tantheta = y/L

d*y/L = m*lambda

lambda = d*y/(L*m)

for d = 0.48 mm = 0.48*10^-3 m

y = 3.05 mm = 3.05*10^-3 m

L = 2.12 m

m = 1 ( first bright fringe)

wavelength lambda = (0.48*10^-3*3.05*10^-3)/(2.12*1) = 690.5 nm <<<<-------ANSWER

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