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MHT CET · Physics · Ray Optics

In an equilateral prism the ray undergoes minimum deviation when it is incident at an angle of \(50^{\circ}\). The angle of minimum deviation is

  1. A \(50^{\circ}\)
  2. B \(40^{\circ}\)
  3. C \(25^{\circ}\)
  4. D \(20^{\circ}\)
Verified Solution

Answer & Solution

Correct Answer

(B) \(40^{\circ}\)

Step-by-step Solution

Detailed explanation

When a ray undergoes minimum deviation,
\(i=\frac{A+\delta_m}{2}\)
For an equilateral triangle,
\(\begin{aligned}
& A=60^{\circ} \\
\therefore \quad & 50=\frac{60+\delta_m}{2} \\
\therefore \quad & \delta_m=40^{\circ}
\end{aligned}\)