Question

A ray of light from a denser medium strikes a rarer medium . the angle of reflection is A and that of refraction is B . the reflected and refracted rays make an angle of 90 degree with each other . The critical angle will be​

Answer 1

Explanation:

Since incident ray is in denser medium we have,

μ

1

=

sinr

′

sini

But r

′

=90

∘

−r and i=r

So,

μ

1

=

sin(90

∘

−r)

sini

=

cosr

sini

=

cosi

sini

=tani

Again if C= Critical angle, then μ=

sinC

1

or

SinC=

μ

1

C=sin

−1

(

μ

1

)

=sin

−1

(tani)

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Answer 2

Answer:

Since incident ray is in denser medium we have,

μ

1

=

sinr

′

sini

But r

′

=90

∘

−r and i=r

So,

μ

1

=

sin(90

∘

−r)

sini

=

cosr

sini

=

cosi

sini

=tani

Again if C= Critical angle, then μ=

sinC

1

or

SinC=

μ

1

C=sin

−1

(

μ

1

)

=sin

−1

(tani)