Physics - Geometrical Optics Question with Solution | TestHub

Paragraph: Light guidance in an optical fiber can be understood by considering a structure comprising of thin solid glass cylinder of refractive index $n_1$ surrounded by a medium of lower refractive index $n_2$. The light guidance in the structure takes place due to successive total internal reflections at the interface of the media $n_1$ and $n_2$ as shown in the figure. All rays with the angle of incidence $i$ less than a particular value $i_m$ are confined in the medium of refractive index $n_1$. The numerical aperture (NA) of the structure is defined as $\sin i_m$.


Question: For two structures namely $S_1$ with $n_1=\sqrt{45}/4$ and $n_2=3/2$, and $S_2$ with $n_1=8/5$ and $n_2=7/5$ and taking the refractive index of water to be $4/3$ and that of air to be $1$ , the correct option(s) is(are)