A typical optical fibre consists of a fine core of a material of refractive index - 1 surrounded by a glass or plastic cladding with refractive index - 2- Then

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Standard XII

Physics

Propagation of Waves

A typical opt...

Question

A typical optical fibre consists of a fine core of a material of refractive index $μ_{1}$ surrounded by a glass or plastic cladding with refractive index $μ_{2}$ . Then

μ_{2}

is slightly less than

μ_{1}

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μ_{2}

is slightly higher than

μ_{1}

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μ_{2}

should be

μ_{1}

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The difference

μ_{2} - μ_{1}

should be strictly equal to

1

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Solution

The correct option is A $μ_{2}$ is slightly less than $μ_{1}$
An optical fibre consists of a fine core of a material of refractive index μ surrounded by a glass or a plastic cladding with refractive index μ2 such that μ2<μ1. The difference Δμ=μ1−μ2 is typically very small of the order of 10−3. An optical fibre is based on the principle of total internal reflection. For total internal reflection to take place refractive index of core should be more than that of the cladding.

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Similar questions

Q. An optical fibre consists of a core having refractive index

μ_{1}

surrounded by a cladding of refractive index

μ_{2}

(μ_{2} < μ_{1})

. A beam of light enters from the air at an angle of

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for which ray can be travelled through fiber is

Q. A right angled prism of refractive index

μ_{1}

is placed in a rectangular block of refractive index

μ_{2}

, which is surrounded by a medium of refractive index

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as shown in the figure. A ray of light

^{'} e^{'}

enters the rectangular block at normal incidence. Depending upon the relationship between

μ_{1}, μ_{2}

and

μ_{3},

it takes one of the four possible paths

^{'} e f^{'},^{'} e g^{'},^{'} e h^{'}

^{'} e i^{'}

Match the paths in

List -I

with conditions of refractive indices in

List -II

and choose the correct answer.
List - I List - II

$(P) e \to f$	$(1) μ_{1} > \sqrt{2} μ_{2}$
$(Q) e \to g$	$(2) μ_{2} > μ_{1} & μ_{2} > μ_{3}$
$(R) e \to h$	$(3) μ_{1} = μ_{2} = μ_{3}$
$(S) e \to i$	$(4) μ_{2} < μ_{1} < \sqrt{2} μ_{2} & μ_{2} > μ_{1}$

Q. Tow optical media of refractive indices

μ_{1}

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x

and

y

number of waves in the same thickness Their relative refractive index

\frac{μ_{2}}{μ_{1}}

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Q. In the figure below a ray of light travelling in a medium of refractive index

μ

passes through two different rectangular blocks of refractive indices

μ_{1}

and

μ_{2} (μ_{2} > μ_{1})

.
The angle of incidence

θ_{1}

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A vessel of depth $2 d c m$ is half filled with a liquid of refractive index $μ_{1}$ and the upper half with a liquid of refractive index $μ_{2}$ . The apparent depth of the vessel seen perpendicularly is

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A typical optical fibre consists of a fine core of a material of refractive index μ1 surrounded by a glass or plastic cladding with refractive index μ2. Then

A typical optical fibre consists of a fine core of a material of refractive index $μ_{1}$ surrounded by a glass or plastic cladding with refractive index $μ_{2}$ . Then