A small transparent slab containing material of μ =1.5 is placed along AS2 (Fig.10.6). What will be the distance from O of the principal maxima and of the first minima on either side of the principal maxima obtained in the absence of the glass slab?

Explanation:-
From the given diagram

For the principal maxima,(path difference is zero)
is the angular position corresponding to the principal maxima.
For the first minima, the path difference is