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>>Total Internal Reflection
>> $Find out no. of reflection after which l$

Question

Find out no. of reflection after which light ray will exit from (Given sin $4 0^{0} = 0.64$ )

1611351

A

$130000$

B

$57735$

C

$140000$

D

$150000$

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Updated on : 2022-09-05

Solution

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Correct option is B)

1 sin $4 0^{0} = 1.31 s i n r$
$0.64 = 1.31 s i n r$
$s i n r = \frac{0 . 6 4}{1 . 3 1} = 0.49 \approx 0.5$
$r = 30$
So $θ = C$
$∵ θ > C$
$∴$ T.I.R. at other surface
$t a n r = \frac{2 0 μ m}{x}$
$x = 203$
$n = \frac{2 m}{2 0 3 μ m}$
$n = \frac{1 0 ^{5}}{3}$
$n = 57735$

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