Statement slit separation young's double slit

[EF17xx]

Homework Statement

For accurate measurement of the fringe separation, a small as possible slit separation should be used.

Homework Equations

s=λD/d

The Attempt at a Solution

Why is this statement correct ?

 

[kuruman]

Why is this statement correct ?

You have quoted a relevant equation. What happens according to that equation as the slit separation becomes smaller? Imagine yourself trying to measure the fringe separation on the screen using a ruler.