The radius $r$ of the $n^{th}$ half-period zone is proportional to:

Light of wavelength $5000 \, \mathring{A}$ is incident on a single slit such that the angular position of the first minima is $30^\circ$. The width of the slit is:

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

Due to which optical phenomenon do we not see the shadow of an opaque object clearly?

In a single slit diffraction pattern, the wavelength of light used is $628 \text{ nm}$ and slit width is $0.2 \text{ mm}$. The angular width of the central maximum is $\alpha \times 10^{-2} \text{ degrees}$. The value of $\alpha$ is . . . . . . . (Take $\pi = 3.14$)

Consider the diffraction pattern obtained from the sunlight incident on a pinhole of diameter $0.1 \, \mu m$. If the diameter of the pinhole is slightly increased,it will affect the diffraction pattern such that :