Question

A screen is placed `50 cm` from a single slit, which is illuminated with `6000 Å` light. If the distance between the first and third minima in the diffraction pattern is `3.00 mm`, what is the width of the slit ?

Answer 1

Given, `D=50 cm and lambda =600nm`
Distance between first and third minima
`y_(3)-y_(1)=(3Dlambda)/a-(Dlambda)/a=(2Dlambda)/a`
`rArr 3xx10^(-3)=(2xx0.5xx600xx10^(-9))/a`
Therefore, width of the slit,
`a=200xx10^(-6)m=0.2mm`