Increase the slit width to 1050 nm. What happens to the width of the central bright fringe? (Always remember to wait a few seconds for the simulation to catch up with the changes you made.)

The width of the central bright fringe becomes narrower.

Explanation:

In case of Single Slit, diffraction will occur.

Then In Single slit Diffraction, width of central fringe is

where D= distance between screen and slit

a= slit width

Thus if Screen width increases keeping other factors same then width of cental fringe becomes narrower as

The width of the central bright fringe becomes narrower.