A monochromatic light beam of wavelength λ is diffracted
i944p l/r:c 5st ccmeh at a single slit of width
cecpht4l/:s94icm 5 r$b$. 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 $w$?