Question

The optical fibres have an inner core of refractive index ${{n}_{1}}$ and a cladding of refractive index ${{n}_{2}},$ such that

• A. ${{n}_{1}}={{n}_{2}}$
• B. ${{n}_{1}}\le {{n}_{2}}$
• C. $ {{n}_{1}}
• D. ${{n}_{1}}>{{n}_{2}}$

Answer 1

Answer: (D)

${{n}_{1}}>{{n}_{2}}$

Answer 2

Optical fibre is made of a thin glass core (diameter 10 to $100\text{ }\mu m$ ) surrounded by a glass coating called cladding is protected by a jacket of plastic. The refractive index of the glass used for making core $({{n}_{1}}\approx 1.7)$ is a little more than the refractive index of the glass $({{n}_{2}}=1.5)$ used for making the cladding ie, ${{n}_{1}}>{{n}_{2}}$ .