Question

g A fiber optic is made by covering a thin fiber core material with a cladding material. An optical fiber works on the principle of total internal reflection, from this we can conclude that: A) The refractive index of the core material is less than the refractive index of the cladding material. B) The refractive index of the cladding material is less than the refractive index of the core material. C) They must have the same refractive index. D) It does not matter what the refractive index is. E) The refractive index of the cladding must be exactly twice that of the core.

Answer 1

Answer:(b)

Explanation:

Optical fiber works on the principle of total internal reflection . Total internal reflection occurs when the following two conditions are met

(1) When the angle of incidence of light is greater than the critical angle and,

(2) When a ray of light travels from a optically denser medium to optically rarer medium .

We know that light bend away from normal when it travels from denser to rarer medium. If we we choose such an angle that the refraction angle is $90^{\circ}$ then the incident angle is called critical angle.

So, the refractive index of cladding must be must be less than the refractive index of core material.