Physical Optics

Physical Optics

Young Double slit experiment:

Young Double Slit Experiment

Here,        AP = AR+PR

                  = D + Xn-d/2

              BP = BR+PQ

                  = D + Xn+d/2

▲APR,

  AP^2=AR^2+PR^2

        = D^2 + (Xn - d/2)^2.......................(1)

▲BPQ,

BP^2 = BQ^2 + PQ^2

       = D^2 + (Xn+d/2)^2...........................(2)

(2)-(1)

BP^2 - AP^2 = {D^2 + (Xn+d/2)^2}-{D^2 + (Xn - d/2)^2}

                = D^2 + (Xn+d/2)^2 - D^2 - (Xn - d/2)^2   

                = Xnd/D

For bright fringes

Xn= (n x Weve length x D)/d