JEE Mains · Physics · STD 12 - Ray optics and optical instruments
- JEE Mains 2026
- Medium
- MCQ
The exit surface of a prism with refractive index \(n\) is coated with a material having refractive index \(\frac{ n }{2}\). When this prism is set for minimum angle of deviation it exactly meets the condition of critical angle. The prism angle is _________
Pick an option to check your answer.
Answer & Solution
Correct Answer
(A) \( 60^{\circ} \)
Step-by-step Solution
Detailed explanation
\(i = e \& r = A / 2\) for minimum deviation

\(\operatorname{Sin} r =\operatorname{Sin} \theta_{ c }\)
\(\operatorname{Sin} r =\frac{ n / 2}{ n }\)
\(\operatorname{Sin} r =\frac{1}{2}\)
\(\operatorname{Sin} \frac{ A }{2}=\sin 30^{\circ}\)
\(\frac{ A }{2}=30^{\circ}\)
\(A =60^{\circ}\)

\(\operatorname{Sin} r =\operatorname{Sin} \theta_{ c }\)
\(\operatorname{Sin} r =\frac{ n / 2}{ n }\)
\(\operatorname{Sin} r =\frac{1}{2}\)
\(\operatorname{Sin} \frac{ A }{2}=\sin 30^{\circ}\)
\(\frac{ A }{2}=30^{\circ}\)
\(A =60^{\circ}\)
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