For a light pipe as shown in the figure:

(A) Optical density of core should be greater than the optical density of cladding
(B) r and θ will always be equal
(C) Optical density of cladding is $\sin θ.\sin i/\sin r$
(D) Optical density of cladding is $\sin r.\sin i /\sin θ$

Choose the correct answer from the options given below:

(A), (C) only

The correct answer is Option (3) → (A), (C) only

(A) In optical fibers, total internal reflection occurs when light travelling in the core reflects off the core-cladding.

for this to happen, optical density (refractive index) of the core should be greater than the cladding.

(C) Optical density of cladding,

$μ=\frac{\sin θ×\sin i}{\sin r}$