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TS EAMCET · Physics · Ray Optics

The principal section of a glass prism is an isosceles triangle \(A B C\) with \(A B=A C\). The face \(A C\) is silvered. A ray of light is incident normally on the face \(A B\) and after two reflections, it emerges from the base \(B C\) perpendicular to the base. Angle \(B A C\) of the prism is

  1. A \(30^{\circ}\)
  2. B \(36^{\circ}\)
  3. C \(60^{\circ}\)
  4. D \(72^{\circ}\)
Verified Solution

Answer & Solution

Correct Answer

(B) \(36^{\circ}\)

Step-by-step Solution

Detailed explanation

\( \begin{array}{llrl} & i_1 =90^{\circ}-\left(90^{\circ}-A\right)=A \\ \text { and } \alpha & =90^{\circ}-21_1=90^{\circ}-2 A \\ \therefore & i_2 =90^{\circ}-\alpha=90^{\circ}-\left(90^{\circ}-2 A\right)=2 A \\ \therefore & \beta =90^{\circ}-i_2=90^{\circ}-2 A \end{array} \)…
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