InterviewSolution
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InterviewSolution
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Distance between the slit shown in figure is `d = 20 lambda`, where `lambda` is the wavelength of light used. Find the angle `theta` where a. central maxima (where path difference is zero) is obtained, and b. third-order maxima is obtained. |
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Answer» Ray 1 has a longer path than that of ray 2 by a distance d `sin 45^(@)` before reaching the slits. Afterwords ray 2 has a path longer than ray 1 by a distance `d sin theta` The net path difference is therefore, `d sin theta -d sin 45^(@)` (i) Central maximum is obtained, where not path difference is zero or `d sin theta-d sin 45^(@) =0 or theta=45^(@)` (ii) Third order maxima is obtained, where net path difference is `3lambda` or `d sin theta -d sin 45^(@)=3lambda` `:. sin theta = sin 45^(@)+(3lambda)/d` Putting `d=20 lambda` we have `sin theta=sin 45^(@)+(3lambda)/(20 lambda) or theta ~~59^(@)` |
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