In a single slit diffraction experiment, the width of the slit is reduced. What happens to the linear width of the principal maxima?

$A$ single slit of width $b$ is illuminated by a coherent monochromatic light of wavelength $\lambda$. If the second and fourth minima in the diffraction pattern at a distance $1\,m$ from the slit are at $3\,cm$ and $6\,cm$ respectively from the central maximum,what is the width of the central maximum in $cm$ (i.e.,distance between the first minimum on either side of the central maximum)?

$A$ light ray of wavelength $\lambda$ is passing through a pinhole of diameter $D$ and the effect is observed on a screen placed at a distance $L$ from the pinhole. The approximations of geometrical optics are applicable, if

The light of wavelength $6328 \ \mathring{A}$ is incident on a slit of width $0.2 \ mm$ perpendicularly. The angular width of the central maxima will be.....$^o$

$A$ screen is placed at a certain distance from a narrow slit,which is illuminated by a parallel beam of monochromatic light. What will you observe if you scan the screen with the help of a microscope?

$A$ beam of light having wavelength $5400 \text{ Å}$ from a distant source falls on a single slit $0.96 \text{ mm}$ wide and the resultant diffraction pattern is observed on a screen $2 \text{ m}$ away. What is the distance between the first dark fringe on either side of the central bright fringe (in $\text{mm}$)?