Consider a two slit interference arrangement

cbse
waveoptics

#1

Consider a two slit interference arrangement (shown in figure) such that the distance of the screen from the slits is half the distance between the slits. Obtain the value of D in terms of λ such that the first minima on the screen falls at a distance D from the centre O.


#2

From the given figure, of two slit interference arrangement, we can write