Physics - Geometrical Optics Question with Solution | TestHub

The ray$\mathrm{PQ}$will undergo minimum deviation in prism$\mathrm{A}$if the angle of the incident on$\mathrm{A}$is such that the refracted ray in$A$is parallel to its base. Since prisms$\mathrm{B}$and$\mathrm{C}$are identical to$\mathrm{A}$and are made of the same materials as$\mathrm{A}$, the refracted ray in$\mathrm{A}$suffers no further deviation by prisms$\mathrm{B}$and$\mathrm{C}$. Hence the emergent ray from prism$\mathrm{C}$will suffer the same deviation as that produced by prism$\mathrm{A}$. Hence the correct choice is$3$.