The width of the $nth$ $HPZ$ (Half Period Zone) will be:

$A$ parallel beam of light of wavelength $\lambda$ is incident normally on a single slit of width $d$. Diffraction bands are obtained on a screen placed at a distance $D$ from the slit. The second dark band from the central bright band will be at a distance given by

The bending of a beam of light around the corners of obstacles is called

In a single slit diffraction pattern, the distance between the first minimum on the left and the first minimum on the right is $5 \,mm$. The screen on which the diffraction pattern is obtained is at a distance of $80 \,cm$ from the slit. The wavelength used is $6000 \mathring{A}$. The width of the slit is (in $\,mm$)

Two wavelengths of sodium light $590 \,nm$ and $596 \,nm$ are used one after another to study diffraction due to a single slit of aperture $2 \times 10^{-6} \,m$. The distance between the slit and the screen is $1.5 \,m$. The separation between the positions of the first maximum of the diffraction pattern obtained in the two cases is: (in $\,mm$)

In a single slit diffraction experiment, the first minimum for red light $(660 \ nm)$ coincides with the first secondary maximum of some other wavelength $\lambda$. The value of $\lambda$ is $..... \mathring{A}$.