Optical Fiber Waveguides MCQ || Types of Optical fiber Waveguides Questions and Answers

Optical Fiber / March 15, 2022

11. According to Hockham how much attenuation (per kilometer) can be reduced in optical fiber.

  1. 10 dB
  2. 30 dB
  3. 20 dB
  4. 100 dB

Answer:3. 20 dB

Explanation:

Hockham promoted the idea that the attenuation in optical fibers Offsite Link could be reduced below 20 dB per kilometer, allowing fibers to be a practical medium for communication. Kao and Hockham proposed that the attenuation in fibers available at the time was caused by removable impurities rather than by fundamental physical effects such as scattering. Eventually, fiber optic communication became the technology enabling the Internet backbone.

 

12. The first generation of optical sources fabricated from _______

  1. Silicon
  2. Gallium Aluminum Arsenide
  3. Silicon Gallium
  4. Silicon Aluminium

Answer:2. Gallium Aluminum Arsenide

Explanation:

During the initial period in optical fiber, most of this work was focused on the 0.8 to 0.9 um wavelength band because the first generation of optical sources fabricated from gallium aluminum arsenide alloys operated in this region.

However, as silica fibers were studied in further detail it became apparent that transmission at longer wavelengths (1.1 to 1.6 um) would result in lower losses and reduced signal dispersion. This produced a shift in optical fiber source and detector.

 

13. In Total internal Reflection of light the angle of incidence in denser medium is ______ than the critical angle

  1. Greater
  2. Smaller
  3. Equal
  4. Can’t say

Answer:1. Greater

Explanation:

Total internal Reflection of light If the angle of incidence in the denser medium is greater than the critical angle (, then the ray is reflected back into the first rarer medium, this phenomenon is called total internal reflection. In a desert, the phenomenon of mirage occurs due to total internal reflection.

 

14. Which of the following are examples of refraction?

  1. Bending of object
  2. Twinkling of Star
  3. Oval shape of sun
  4. All of the above

Answer:4. All of the above

Explanation:

When a ray of light propagating in a medium enters the other medium, it deviates from its path. This phenomenon of change in the direction of propagation of light at the boundary, when it passes from one medium to another medium, is called the refraction of light.

Example of Refraction

  1. Bending of a linear object when it is partially dipped in a liquid inclined to the surface of the liquid.
  2. Twinkling of stars.
  3. The oval shape of the sun in the morning and evening.
  4. An object in a denser medium, when seen from a rarer medium, appears to be at a smaller distance.
  5. Due to refraction, rivers appear shallow, coin in a beaker filled with water appears raised, pencil in the beaker appears broken.
  6. At sunset and sunrise, due to refraction, the sun appears above the horizon while it is actually below the horizon. The duration of the day appears to be increased by nearly 4 minutes to atmospheric refraction.
  7. Writing on a paper appears lifted when a glass slab is placed over the paper.

 

15. Which of the following are examples of Total internal reflection?

  1. Diamond Sparkling
  2. Mirage
  3. Shining of air bubble in water
  4. All of the above

Answer:4. All of the above

Explanation:

Total internal Reflection of light If the angle of incidence in the denser medium is greater than the critical angle (, then the ray is reflected back into the first rarer medium, this phenomenon is called total internal reflection. In a desert, the phenomenon of mirage occurs due to total internal reflection.

Example of Total Internal Reflection

i. Sparkling of the diamond.

ii. Mirage and looming.

iii. Shining of air bubble in water.

iv. Increase in duration of sun’s visibility.

v. Shining of a smoked ball or a metal ball on which lamp stool deposited when dipped in water.

vi. Optical Fibre.

 

16. What is the application of Total internal Reflection?

  1. Optical Fiber
  2. Electrical Field
  3. Medical Field
  4. All of the above

Answer:4. All of the above

Explanation:

I. For transmitting optical signals and the two-dimensional picture.

ii. For transmitting electrical signals by first converting them to light.

iii. For visualizing the internal sites of the body by doctors in endoscopy.

 

17. Which equations are best suited for the study of electromagnetic wave propagation?

  1. Maxwell’s equations
  2. Allen-Cahn equations
  3. Avrami equations
  4. Boltzmann’s equations

Answer:1. Maxwell’s equations

Explanation: 

In his formulation of electromagnetism, Maxwell described light as a propagating wave of electric and magnetic fields. More generally, he predicted the existence of electromagnetic radiation: coupled electric and magnetic fields traveling as waves at a speed equal to the known speed of light.

Electromagnetic mode theory finds its basis in electromagnetic waves. Electromagnetic waves are always represented in terms of electric field E, magnetic field H, electric flux density D, and magnetic flux density B. These sets of equations are provided by Maxwell’s equations.

 

18. The phenomenon which occurs when an incident wave strikes an interface at an angle greater than the critical angle with respect to the normal to the surface is called as ____________

  1. Refraction
  2. Partial internal reflection
  3. Total internal reflection
  4. Limiting case of refraction

Answer:3. Total internal reflection

Explanation:

Total internal Reflection of light If the angle of incidence in the denser medium is greater than the critical angle C, then the ray is reflected back into the first rarer medium, this phenomenon is called total internal reflection. Critical angle is an angle beyond which no propagation takes place in an optical fiber. In a desert, the phenomenon of mirage occurs due to total internal reflection.

Example of Total Internal Reflection

i. Sparkling of the diamond.

ii. Mirage and looming.

iii. Shining of air bubble in water.

iv. Increase in duration of sun’s visibility.

v. Shining of a smoked ball or a metal ball on which lamp stool deposited when dipped in water.

vi. Optical Fibre.

 

19. When λ is the optical wavelength in a vacuum, k is given by k=2π/λ. What does k stand for in the above equation?

  1. Phase propagation constant
  2. Dielectric constant
  3. Boltzmann’s constant
  4. Free-space constant

Answer: 1. Phase propagation constant

Explanation: 

In the above equation, k = 2π/λ also termed as the wave equation, k gives us the direction of propagation and also the rate of change of phase with distance. The wave vector k counts the wavenumber (number of nodes) in a particular direction. Hence it is termed as phase propagation constant.

 

20. What is refraction?

  1. Bending of light waves
  2. Reflection of light waves
  3. Diffusion of light waves
  4. Refraction of light waves

Answer:1. Bending of light waves

Explanation:

When a ray of light propagating in a medium enters the other medium, it deviates from its path. This phenomenon of change in the direction of propagation of light at the boundary, when it passes from one medium to another medium, is called the refraction of light.

Example of Refraction

  1. Bending of a linear object when it is partially dipped in a liquid inclined to the surface of the liquid.
  2. Twinkling of stars.
  3. The oval shape of the sun in the morning and evening.
  4. An object in a denser medium, when seen from a rarer medium, appears to be at a smaller distance.
  5. Due to refraction, rivers appear shallow, coin in a beaker filled with water appears raised, pencil in the beaker appears broken.
  6. At sunset and sunrise, due to refraction, the sun appears above the horizon while it is actually below the horizon. The duration of the day appears to be increased by nearly 4 minutes to atmospheric refraction.
  7. Writing on a paper appears lifted when a glass slab is placed over the paper.

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