A monochromatic light beam of wavelength λ is d
e55x :6cw x*oijmku2jiffracted at a single slit of width
c*5 5im 2w6kxox:j uje$b$. 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 $w$?