10 QA on optical fibers | Learn Physics

10 Question-Answer on optical fibers

1.       The main objective of an optical source is:

(a)    To demodulate the electrical signal

(b)   To detect the signal

(c)    To convert the electrical energy into an optical energy

(d)   All of these

Ans: ( c)

2.       The number of telephonic messages which are carried by a fiber at an instant with much less intensity loss are

(a)    2400

(b)   2200

(c)    2000

(d)   1800

Ans: ( c)

3.       Lasers are used in alignment because

(a)    They are coherent

(b)   They are highly directional

(c)    Both (a) and (b)

(d)   None of these

Ans: ( c)

4.       Which fibers are less expensive and simple to construct?

(a)    Single-mode step index fiber

(b)   Multi-mode step index fiber

(c)    Multi graded-index fiber

(d)   All are equally expensive.

Ans: (b)

5.       A laser is a coherent source because it contains

(a)    Many wavelength

(b)   Uncoordinated wave of particular wave length

(c)    Coordinated waves of many wavelength

(d)   Coordinated waves of particular wave length

Ans: ( d)

6.       The population inversion in helium-neon laser is produced by

(a)    Photon excitation

(b)   Electron excitation

(c)    Inelastic atomic collisions

(d)   Chemical reaction

Ans:( b)

7.       In He-Ne laser the most favorable ratio of helium to neon for satisfactory laser action is:

(a)    1:4

(b)   4:1

(c)    1:7

(d)   7:1

Ans: (d)

8.       The population inversion necessary for laser action used in solid state laser is:

(a)    Electrical discharge

(b)   Inelastic atom-atom collisions

(c)    Direct conversion

(d)   Optical pumping

Ans: (d)

9.       Small values of numerical aperture(NA) decrease the pulse dispersion but increase losses due to

(a)    Scattering

(b)   Absorption

(c)    Bending

(d)   Micro bending

Ans: ( d)

10.   The difference in the refractive index of the fiber core and fiber cladding in step-index fiber is typically

(a)    0.01%

(b)   1%

(c)    10%

(d)   25%

Ans: (b)