A monochromatic light beam of wavelength λ
ors)t8n 6w+ux6hw9hee3 p i+x is diffracted at a single slit of width
9x6 )pn twi8e+r+u6eh o3 sxwh$b$. 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 $w$?