The optical fibres have an inner core of refractive index `n_(1)` and a cladding of refractive index `n_(2)`, such that

Options

A. A)`n_(1)=n_(2)`
B. B)`n_(1)len_(2)`
C. C)`n_(1)ltn_(2)`
D. D)`n_(1)gtn_(2)`

Answer

D

Explanation

Optical fibre is made of a thin glass core (diameter 10 to 100 `mu m`) surrounded by a glass coating called cladding is protected by a jacket of plastic.
The refractive index of the glass used for making core `(n_(1)~~1.7)` is a little more than the refractive index of the glass `(n_(2)=1.5)` used for making the cladding i.e., `n_(1)gtn_(2)`.