A monochromatic light beam of wav
jrroew4 b;96selength λ is diffracted at a single slit of widt
sw4bo;6 rejr9 h $b$. 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 $w$?