A monochromatic light bea
oilds1 y d-ud ujpp9ln13lp l:(d:. x1m of wavelength λ is diffracted at a single slit of wid
pndp1ju(-.odsll lx9d pl1d:u:1 y 3ith $b$. 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 $w$?