A monochromatic light beam of wavelengt
)m hx )iv06drt )ozho0hf::gp h λ is diffracted at a single slit of wid
):)zi 6hdr0ohmf 0xop):vhg tth $b$. 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 $w$?