A monochromatic light beam of wavel
r7cv4ga / aqypk t:f3+ength λ is diffracted at a single slit of width
k+43arv f/:y7pcga tq $b$. 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 $w$?