Answer
given,
refractive index of glass (n₁)= 1.60
refractive index of cladding,(n₂) = 1.48
We need to find the critical angle θ in the core such that the refracted angle in the cladding is 90°
Using Snell's Law we have
n₁ x sin (θ₁ ) = n₂ x sin(θ₂)
θ₂ = 90°
n₁ x sin (θ₁ ) = n₂ x sin(90°)
[tex]\theta_1 = sin^{-1}(\dfrac{n_2}{n_1})[/tex]
[tex]\theta_1 = sin^{-1}(\dfrac{1.48}{1.60})[/tex]
[tex]\theta_1 = sin^{-1}(0.925)[/tex]
θ₁ = 67.67°
But this angle is measured from the normal.
so, angle from the wall
= 90° - 67.67°
= 22.33°
