Question

A ray of light is incident at an angle i from denser to rarer medium. The reflected and refracted rays mutually perpendicular. The angle of reflection and the angle of refraction are respectively r and r', then the critical angle will be
a) sin-'(sin r)
b) sin-'tan r')
c) sin-(tan i)
d) tan-'(sin i)​

Answer 1

Answer:

Correct option is

C

sin

−1

(tani)

as the reflected and refracted rays are 90 then the angle of refraction is 90−i

according to Snell's law

siniμ

r

=sin(90−i)

μ

r

=coti

critical angle is sin

−1

μ

r

1

=sin

−1

coti

1

=sin

−1

tani

option C is correct