Physics - Geometrical Optics Question with Solution | TestHub

Critical angle for the glass-air system: ${\theta }_C={\sin }^{-1}(1/\mu )=45^{\circ }$.

(P) $A=100^{\circ }$: incidence at QR exceeds $45^{\circ }$, so TIR at QR: P$\to 1$. (Q) $A=30^{\circ }$: ray meets QR along its normal and emerges normally: Q$\to 2$.

(R) $i=90^{\circ }$ grazing incidence, $A=90^{\circ }$: ray emerges parallel to QR, parallel to base PR inside: R$\to 3,5$.

(S) normal incidence, $60^{\circ }$ prism: incidence at QR is $60^{\circ }>45^{\circ }$ so TIR, and inside the ray is parallel to base PR: S$\to 1,5$. Option (A).