The velocity of light in a medium is half its velocity in air. If ray of light emerges from such a medium into air, the angle of incidence, at which it will be totally internally reflected, is

15^{\circ}

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30^{\circ}

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25^{\circ}

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35^{\circ}

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Solution

The correct option is D $35^{\circ}$
$μ = \frac{c}{v} \Rightarrow μ = \frac{c}{\frac{c}{2}} = 2$ also for total internal reflection
$i > c \Rightarrow s i n i \geq s i n c \Rightarrow s i n i \geq \frac{1}{μ}$
Hence $i > s i n^{- 1} (\frac{1}{μ}) o r i > 30^{\circ}$

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The velocity of light in a medium is half its velocity in air. If ray of light emerges from such a medium into air, the angle of incidence, at which it will be totally internally reflected, is

The correct option is D 35∘μ=cv⇒μ=cc2=2 also for total internal reflection i>c⇒sini≥sinc⇒sini≥1μ Hence i>sin−1(1μ)ori>30∘

The correct option is D $35^{\circ}$
$μ = \frac{c}{v} \Rightarrow μ = \frac{c}{\frac{c}{2}} = 2$ also for total internal reflection
$i > c \Rightarrow s i n i \geq s i n c \Rightarrow s i n i \geq \frac{1}{μ}$
Hence $i > s i n^{- 1} (\frac{1}{μ}) o r i > 30^{\circ}$