What will be the angle of diffraction for the first minimum due to Fraunhofer diffraction with a source of light of wavelength $550 \,nm$ and a slit of width $0.55 \,mm$ (in $,rad$)?

In Fraunhofer diffraction,draw the graph of the intensity of light on the screen versus the diffraction angle $\theta$ and write its characteristics.

In a Fraunhofer diffraction experiment at a single slit using light of wavelength $400 \ nm$,the first minimum is formed at an angle of $30^{\circ}$. The direction $\theta'$ of the first secondary maximum is given by

In Fresnel diffraction,if the distance between the disc and the screen is decreased,the intensity of the central bright spot will

Consider the following statements $A$ and $B$ and identify the correct answer:
$A$. Fresnel's diffraction pattern occurs when the source of light or the screen on which the diffraction pattern is seen,or when both are at a finite distance from the aperture.
$B$. Diffracted light can be used to estimate the helical structure of nucleic acids.

In Fraunhofer diffraction pattern,slit width is $0.3 \ mm$ and screen is at $1.5 \ m$ away from the lens. If wavelength of light used is $4500 \ Å$,then the distance between the first minimum on either side of the central maximum is [ $\theta$ is small and measured in radian.] (in $mm$)