Two point sources separated by $d=5 \mathrm{\mu m}$ emit light of wavelength $\lambda =2 \mathrm{\mu m}$ in phase. A circular wire of radius $20 \mathrm{\mu m}$ is placed around the source as shown in figure.

Two coherent narrow slits emitting light of wavelength $\lambda$ in the same phase are placed parallel to each other at a small separation of $3\lambda .$ The light is collected on a screen $S$ which is placed at a distance $D(>>\lambda )$ from the slits. The smallest distance $x$ such that the $P$ is a maxima.

In the YDSE shown the two slits are covered with thin sheets having thickness $t \text{\&} 2t$ and refractive index $2\mu$ and $\mu .$ Find the position $\left(y\right)$ of central maxima

Light of wavelength $650 \mathrm{nm}$ is incident normally upon a glass plate. The glass plate rests on top of a second plate so that they touch at one end and are separated by $0.0325 \mathrm{mm}$ at the other end as shown in the figure.

Which range of values contains the horizontal separation between adjacent bright fringes?

The phenomenon of diffraction of light was discovered by,