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

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 $,rad$)?

The angular separation of the central maximum in the Fraunhofer diffraction pattern is measured. The slit is illuminated by light of wavelength $6000 Å$. If the slit is illuminated by light of another wavelength,the angular separation decreases by $20 \%$. The wavelength of light used is (in $Å$)

$A$ light beam of wavelength $800 \,nm$ passes through a single slit and is projected on a screen kept at $5 \,m$ away from the slit. What should be the slit width for the ray optics approximation to be valid (in $\,mm$)?

For what distance is ray optics a good approximation when the aperture is $ 4 \,mm $ and the wavelength of light is $ 400 \,nm $ (in $\,m$)?

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