When you look at a clear blue sky, you see tiny specks and hair-like structures floating in your view, called "floaters". This is basically

When light is incident on a diffraction grating,the zero-order principal maximum will be:

Light of wavelength $\lambda$ is incident on a single slit of width $a$,and the distance between the slit and the screen is $D$. In the diffraction pattern,if the slit width is equal to the width of the central maximum,then $D=$

In the diffraction pattern of a single slit,the width of the secondary maxima compared to the central maximum is:

Light of wavelength $\lambda$ is incident on a slit of width $a$. The resulting diffraction pattern is observed on a screen placed at a distance $D$. If the linear width of the central maximum is equal to the width of the slit,then $D = $ . . . . . . .

Red light of wavelength $625 \, nm$ is incident normally on an optical diffraction grating with $2 \times 10^{5} \, \text{lines}/m$. Including the central principal maxima, how many maxima may be observed on a screen which is far from the grating?