A parallel beam of light is incident from air at an angle $α$ on the side PQ of a right angled triangular prism of refractive index $n = \sqrt{2}$ . Light undergoes total internal reflection in the prism at the face PR when $α$ has a minimum value of $45^{o} .$ The angle $θ$ of the prism is:

Question

Question diagram: A parallel beam of light is incident from air at an angle α

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Answer:

A

Solution:

$1 \sin 45^{o} = \sqrt{2} \sin r_{1}$
$r_{2} - r_{1} = θ$
$θ = 45^{o} - 30^{o}$
$\Rightarrow θ = 15^{o}$

TestHub · Accepted Answer

1 sin ⁡ 45 o = 2 sin ⁡ r 1 r 2 - r 1 = θ θ = 45 o - 30 o ⇒ θ = 15 o

Physics - Geometrical Optics Question with Solution | TestHub

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