InterviewSolution
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InterviewSolution
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In the arrangment shown in fin. For what minimum value of d is there a dark bant at point O on the screen?A. `sqrt((D lambda)/(4))`B. `sqrt((3D lambda)/(4))`C. `sqrt((D lambda)/(8))`D. `sqrt((2D lambda)/(43)` |
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Answer» Correct Answer - a For dark spot at O, `Delta x = (AB + BO) - AO` `= 2(D^(2) + d^(2))^(1//2) - 2 D = 2D [(1 + (d^(2))/(D^(2)))^(1//2)-1]` `implies Delta x =(d^(2))/(D)` `(d^(2))/(D) = (lambda)/(2) implies d = sqrt((D lambda)/(4)` `Detla x` at P: `Delta x = (AB + BP) - (AC + PC)` `= (AB - AC) + (BP - PC)` `Delta x` at O: `Delta x = (lambda)/(2)` The path difference at P will be zero if `x = d`. Hence next maxima will front at P. Fringe width = distance between two consecutive dark to brigth fringes `= 2 xx` distance between two consective bright dark fringes `= 2 xx d` |
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