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Question
In deriving the single slit diffraction pattern, it was stated that the intensity is zero at angles of nλ/a. Justify this by suitably dividing the slit to bring out the cancellation.
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Solution
Consider that a single slit of width d is divided into n smaller slits.
∴ Width of each slit, `"d'" = "d"/"n"`
Angle of diffraction is given by the relation,
`theta = ("d"/"d'" lambda)/"d" = lambda/"d'"`
Now, each of these infinitesimally small slits sends zero intensity in directionθ. Hence, the combination of these slits will give zero intensity.
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