A light ray is incident perpendicular to one face of a 90° prism and is totally internally reflected at the glass-air interface. If the angle of reflection is 45°, we conclude that the refractive index n

Question

A light ray is incident perpendicular to one face of a 90° prism and is totally internally reflected at the glass-air interface. If the angle of reflection is 45°, we conclude that the refractive index n (A) n < (1/2) (B) n >√2 (C) n > (1/√2) (D) n < √2

Tardigrade Admin · Accepted Answer

Angle of incidence i > C for total internal reflection. Here i = 45° inside the medium. ∴ 45° > sin-1(1/n) ⇒ n > √2.

Q. A light ray is incident perpendicular to one face of a $9 0^{\circ}$ prism and is totally internally reflected at the glass-air interface. If the angle of reflection is $4 5^{\circ}$ , we conclude that the refractive index $n$

$n < \frac{1}{2}$

$n > 2$

$n > \frac{1}{2}$

$n < 2$

Angle of incidence $i > C$ for total internal reflection.
Here $i = 4 5^{\circ}$ inside the medium.
$∴ 4 5^{\circ} > s i n^{- 1} (1/ n)$
$\Rightarrow n > 2 .$

Q. A light ray is incident perpendicular to one face of a 90∘ prism and is totally internally reflected at the glass-air interface. If the angle of reflection is 45∘, we conclude that the refractive index n

n<21​

n>2​

n>2​1​

n<2​