A monochromatic light beam of wavelen
w28wfwx(lhn6 i .vkd9k gt6/ pgth λ is diffracted at a single slit of wid
wi 2dg phw6k l8/w.v6n(xktf 9th $b$. After passing the slit, a diffraction pattern is observed on a screen a large distance away. The width of the central maximum is $w$.
The screen is moved closer to the slit. Which of the following changes, done separately, could result in no change in $w$?