The limit of resolution of a telescope and a microscope is imposed because of which phenomenon?

The cause of Fraunhofer lines is

$A$ student is jogging on a straight path with a speed of $5.4 \,km/h$. Perpendicular to the path is a pipe with its opening $8 \,m$ from the road (see figure). The diameter of the pipe is $0.45 \,m$. At the other end of the pipe is a speaker emitting sound of $1280 \,Hz$ towards the opening of the pipe. As the student passes in front of the pipe,she hears the speaker sound for $T$ seconds. $T$ is in the range (Take speed of sound $= 320 \,m/s$):

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 $mm$)

For an aperture of $5 \times 10^{-3} \ m$ and a monochromatic light of wavelength $\lambda$, the distance for which ray optics becomes a good approximation is $50 \ m$, then $\lambda=$ (in $\text{Å}$)

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