What is the effect of the distance to the screen on the interference pattern in Young’s experiment?

In Young’s double-slit experiment, the distance between the slits and the screen (often denoted as L) affects the interference pattern as follows:

1. Fringe spacing increases with distance:
   As the screen moves farther away from the slits, the fringes spread out more, meaning the distance between adjacent bright or dark fringes (fringe width) becomes larger.
2. Fringes become easier to observe:
   With increased distance, the fringes are more widely spaced, making them easier to see and measure.
3. Pattern remains the same type:
   The overall pattern of alternating bright and dark fringes stays the same; only the scale changes.

Why this happens:

The fringe width is proportional to the distance between the slits and the screen because the path difference between waves translates into larger spatial separations on a more distant screen.