In the refraction through a triangular prism, which is not true in ca…

The correct answer is Option (3) → Angle of refraction at first face > angle of incidence at second face

At minimum deviation the ray passes through the prism symmetrically, so \( i = e \) and \( r_1 = r_2 \). Since \( r_1 + r_2 = A \), each angle of refraction is \( A/2 \).

Option (1) Refracted ray is parallel to the base of prism — Correct statement. By symmetry the ray inside travels parallel to the base (for the usual isosceles or equilateral prism).

Option (2) Angle of incidence = angle of emergence — Correct statement. The path is symmetric, so \( i = e \).

Option (3) Angle of refraction at first face > angle of incidence at second face — Not true. At minimum deviation \( r_1 = r_2 \), so the angle of refraction at the first face equals the angle of incidence at the second face; it is not greater.

Option (4) Angle of incidence at second face = \( \displaystyle\frac{\text{Angle of Prism}}{2} \) — Correct statement. \( r_2 = A/2 \) from \( r_1 + r_2 = A \) with \( r_1 = r_2 \).

NCERT (2026-27):
Refraction Through a Prism – “… At the minimum deviation D_m, the refracted ray inside the prism becomes parallel to its base. We have \( \delta = D_m \), \( i = e \) which implies \( r_1 = r_2 \). Equation (9.34) gives

    \( \displaystyle 2r = A \quad \text{or} \quad r = \frac{A}{2} \qquad (9.36) \)”