# The angle of incidence on the surface of a diamond of refractive index 2.4, if the angle between the reflected and refracted rays is 90° is

Q.The angle of incidence on the surface of a diamond of refractive index 2.4, if the angle between the reflected and refracted rays is 90° is
(a) tan-1(2.4)
(b) sin-1(1/2.4)
(c) tan-1 (1/2.4)
(d) cos-1 (1/2.4)
Ans: A

Sol: According to question , i+r=90°  ….(i)

Applying Snell’s Law

1×sini = 2.4×sinr

sini = 2.4×sin(90-i) = 2.4cosi from(i)

tani = 2.4

i = tan−1(2.4)

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