A) \[\frac{d{{e}^{2}}}{6D}\]
B) \[\frac{{{d}^{2}}}{9D}\]
C) \[\frac{{{d}^{2}}}{15D}\]
D) \[\frac{{{d}^{2}}}{9D}\]
Correct Answer: D
Solution :
For dark fringe, \[\frac{xd}{D}=(2m-1)\frac{\lambda }{2}\] Here, \[m=5,\] \[x=\frac{d}{2}\] \[\therefore \] \[\frac{d}{2}.\frac{d}{D}=(2\times 5-1)\frac{\lambda }{2}\] or \[\frac{{{d}^{2}}}{D}=9\lambda \] \[\therefore \] \[\lambda =\frac{{{d}^{2}}}{9D}\]You need to login to perform this action.
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