Question

in optical fibre the refractive index of the core is

1)greater than that of the cladding.

2)equal to that of the cladding.
smaller than that of the cladding.

3)independent of that of cladding.

4)Other​

Answer 1

Answer:

1)greater than that of the cladding

Explanation:

Assume that the core material was optically rarer than the cladding. Then, the electromagnetic pulses (basically light) would escape the cable and go out. Similar to the case when light is incident on a glass slab of higher refractive index.

This defeats the purpose of an optical fiber. The sole principle of its working is Total Internal Reflection, a process that happens only when light is incident on a medium, where the second medium is optically rarer than the first.

Also, this can be proved mathematically if one uses this equation—

n2,1=1sinθi

Where n2,1 is the refractive index of the second medium with respect to the first. In this case, it is the refractive index of the core with respect to the cladding.

Since the sine of any acute angle lies between 0 and 1, its reciprocal will always result in a number greater than 1.

Thus, if n2,1 is greater than 1, it means that the refractive index of the core is greater than the cladding.

Answer 2

Answer:

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