Question

The angle of a glass prism is 4.5° and its refractive index is 1.52. The angle of minimum deviation will be -

• A. 1.5°
• B. 2.3°
• C. 4.5°
• D. 2°

Answer 1

Answer: (B)

2.3°

Answer 2

For a small-angled prism (angle $A \le 10^\circ$), the angle of minimum deviation ($\delta_m$) can be approximated by the formula $\delta_m = A(n-1)$, where $A$ is the prism angle and $n$ is the refractive index. Given $A = 4.5^\circ$ and $n = 1.52$, substitute these values: $\delta_m = 4.5^\circ (1.52 - 1) = 4.5^\circ (0.52) = 2.34^\circ$. This value is approximately $2.3^\circ$.