^Position of minima

^Position of minima

Path difference between the wavefronts reaching P from the end of the slits B & A is, x or p = BP – AP = AN Also p = d sinθ =

A detailed mathematical analysis shows that at P for n^th minima p = d sinθ = nl, n = ± 1, ± 2, ± 3, _ _ _

For small θ, sinθ » θ

Thus angular position of nth dark fringe is

i.e. angular positions of 1^st, 2^nd, 3^rd minima are