1.

A beam of light of lambda= 600 nm from a distant source falls on a single slit 1 mm wide and the resulting diffraction pattern is observed on a screen 2 m away. The distance between first dark fringes on either side of the central bright fringe is ...

Answer»

`1.2` cm
`1.2`mm
`2.4` cm
`2.4` mm

Solution :CONDITION for FIRST MINIMUM,
`d sin thea_(1)= lambda`
`:. sin theta_(1)=(lambda)/(d)`
but `sin theta_(1)=(x_(1))/(D)`
`:. (x_(1))/(D)=(lambda)/(d)`
`:.x_(1)=(lambdaD)/(d)`
`:.` The distance between first minimum from central maximum on both the SIDES `=2x_(1)`
`:.2x_(1)=(2lambdaD)/(d)`
`=(2xx600xx10^(-9)xx2)/(1xx10^(-3))`
`=2400xx10^(-6)m=2.4 mm`


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