A monochromatic light beam of wavelengt
o axzmm3r3lh/7oxg :3y impnn+1 w*j0h λ is diffracted at a single slit of width
ml7ap i mw*/10rxh gy+x33o 3 omjz:nn$b$. 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 $w$?