Question

The refractive index of medium in which the total internal reflection just begins to take place at an angle of 45 degrees.
a. 1.3

b. 1.5
c. 1.4
d. 1.6
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Answer 1

Answer:

Correct option is

C

μ=1.50

For total internal reflection,

sin i > sin c

where, i = angle of incidence, C = critical angle

But, sinC=

μ

1

∴sini=

μ

1

orμ=

sini

1

∴μ>

sin45

1

orμ>

2

(i=45Given)

Hence, option (c) is correct.