A monochromatic light beam of wavelength λ is diffr
xg(ph(xv e )p* a*yh:ux-vm6dacted at a single slit of width
v)vu* x(- g6p: dmehpyx*x( ha $b$. 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 $w$?