Light of wavelength $6328 \, \mathring{A}$ is incident on a slit of width $0.2 \, mm$. Find the angular width of the central maximum on a screen at a distance of $9 \, m$ in degrees.

The luminous border that surrounds the profile of a mountain just before the sun rises behind it is an example of:

Red light is generally used to observe a diffraction pattern. If green light is used instead of red light,the diffraction pattern will.....

$A$ Fraunhofer diffraction pattern due to a single slit of width $0.3 \text{ mm}$ is obtained on a screen placed at a distance of $3 \text{ m}$ from the slit. The first minima lie at $5.5 \text{ mm}$ on either side of the central maximum on the screen. The wavelength of light used is (in $\text{ Å}$)

$A$ slit of width $a$ is illuminated by monochromatic light of wavelength $650 \ nm$. The value of $a$ when the first maximum is formed at a diffraction angle of $30^\circ$ is:

$A$ circular disc is placed in front of a narrow source. When the point of observation is at a distance of $1 \, m$ from the disc,the disc covers the first $HPZ$ (Half Period Zone). The intensity at this point is $I_0$. The intensity at a point at a distance of $25 \, cm$ from the disc will be: