Fiber Optics Engineering Quiz

Podcast

Play an AI-generated podcast conversation about this lesson

Questions and Answers

What is the primary characteristic of graded-index fiber?

Density is highest at the edges of the core.

It is exclusively used in multimode applications.

Density varies with the highest at the center of the core. (correct)

It has uniform density throughout.

What type of fiber uses a highly focused light source that limits beams to a small range of angles?

Plastic optical fiber

Graded-index fiber

Multimode fiber

Single-mode fiber (correct)

What is the diameter of the core in a typical single-mode fiber?

100 µm

7 µm (correct)

50 µm

62.5 µm

How does the density of the single-mode fiber compare to that of multimode fiber?

Single-mode fiber has a lower density than multimode fiber. Signup and view all the answers

What is the cladding diameter for the multimode fibers listed?

125 µm Signup and view all the answers

Which layer in a fiber-optic cable provides strength to the cable composition?

Outer jacket Signup and view all the answers

What is the primary benefit of single-mode fiber in terms of signal propagation?

Enables almost identical propagation of different beams. Signup and view all the answers

Which materials are common for the outer jacket of typical fiber-optic cables?

PVC or Teflon Signup and view all the answers

What is the primary function of a fiber-optic cable?

To transmit signals in the form of light Signup and view all the answers

What happens to a ray of light when it enters a less dense substance at an angle greater than the critical angle?

It reflects back into the denser substance Signup and view all the answers

What determines the critical angle for a substance?

The density of the substance Signup and view all the answers

How does optical fiber guide light through a channel?

By reflection from the cladding surrounding the core Signup and view all the answers

If the angle of incidence is equal to the critical angle, what will occur?

The ray will bend along the interface. Signup and view all the answers

What is the role of the cladding in a fiber-optic cable?

To create a reflective surface for light guidance Signup and view all the answers

Which of the following statements is false regarding the path of light in optical fibers?

Light reflects off the core to enter the cladding. Signup and view all the answers

What must be true for light traveling in the core of a fiber-optic cable to be reflected off the cladding?

The difference in densities must be sufficient to enable this reflection. Signup and view all the answers

Which of the following best defines a transmission medium?

A pathway that carries information from source to destination Signup and view all the answers

What role does the physical layer play in relation to transmission media?

It manages how data signals travel through the medium Signup and view all the answers

Which statement best describes the nature of communication before the invention of the telephone?

Telegraph communication was dependent on a metallic medium. Signup and view all the answers

Which of the following mediums was commonly used for early telephone communication?

Metallic cables Signup and view all the answers

What was a significant limitation of early telephonic communication?

The unreliability due to noisy transmissions Signup and view all the answers

When was the concept of wireless communication first introduced?

1895 Signup and view all the answers

What fundamental technology did the telegraph rely upon?

Metallic mediums to carry electric signals Signup and view all the answers

Which of the following is an example of a non-physical transmission medium?

Air used in conversation Signup and view all the answers

What is the frequency range typically classified as radio waves?

3 kHz to 1 GHz Signup and view all the answers

Which characteristic of radio waves allows them to be received without aligning the sending and receiving antennas?

Omnidirectional propagation Signup and view all the answers

What is a significant disadvantage of radio wave transmission's omnidirectional property?

Interference by other signals Signup and view all the answers

Which application primarily utilizes the omnidirectional characteristics of radio waves?

Multicasting Signup and view all the answers

What is a consequence of radio waves' ability to penetrate walls?

Reception inside buildings Signup and view all the answers

Which factor contributes to the low data rate of digital communications in the radio wave band?

Narrow frequency band Signup and view all the answers

What must be obtained to use any part of the radio wave band?

Permission from regulatory authorities Signup and view all the answers

What type of antenna is commonly used to transmit radio waves?

Omnidirectional antenna Signup and view all the answers

What is the primary advantage of using Kevlar in fiber-optic cables?

It strengthens the cable and provides cushioning. Signup and view all the answers

Which connector is specifically used for cable TV applications?

SC connector Signup and view all the answers

What is the main feature of the ST connector?

It employs a bayonet locking system. Signup and view all the answers

How does the attenuation of fiber-optic cables compare to twisted-pair and coaxial cables?

It is consistently lower across all wavelengths. Signup and view all the answers

What is the effect of using fiber-optic cables on the number of repeaters needed?

Fewer repeaters are needed compared to other cable types. Signup and view all the answers

What is the benefit of wavelength-division multiplexing (WDM) in fiber-optic technology?

It allows multiple data transmissions over a single fiber. Signup and view all the answers

What is the typical data transfer rate achievable with fiber-optic cables using WDM technology?

1600 Gbps Signup and view all the answers

Where is fiber-optic cable commonly utilized due to its characteristics?

In backbone networks Signup and view all the answers

What advantage does optical fiber have in terms of signal attenuation compared to coaxial cable?

Signal can run for longer distances without needing regeneration. Signup and view all the answers

Which characteristic of optical fiber makes it immune to electromagnetic interference?

Transmission via light instead of electrical signals. Signup and view all the answers

What is a significant disadvantage of using optical fiber technology?

Installation and maintenance require specialized expertise. Signup and view all the answers

Why do some cable TV companies prefer to use a hybrid network with optical fiber and coaxial cable?

The bandwidth requirement at the user end is low. Signup and view all the answers

What is the primary reason that fiber-optic cables have a greater immunity to unwanted tapping?

Copper cables create antenna effects that can be easily tapped. Signup and view all the answers

What is a reason that manufacturers may not justify the use of optical fiber if bandwidth demand is low?

Higher cost of cable and interfaces. Signup and view all the answers

What type of light propagation is characteristic of fiber-optic cables?

Unidirectional propagation requiring multiple fibers for two-way communication. Signup and view all the answers

What aspect of fiber-optic cables contributes to their relative light weight compared to copper cables?

The physical properties of glass versus copper. Signup and view all the answers

Signup and view all the answers

Study Notes

Transmission Media

Transmission media are located below the physical layer, controlled by it. They can be considered layer zero.
Transmission media is anything that carries information from a source to a destination, which can include air, mail carriers, or airplanes.
In data communications, transmission media is usually free space, metallic cable, or fiber-optic cable.

Transmission Medium Definitions

A transmission medium carries information from a source to a destination.
In data communications, it is more specific, typically involving signal conversion from data.
The medium often consists of electrical signals, examples include telegraph (Morse code), and telephone (converting human voice).

Guided Media

Guided media include twisted-pair cable, coaxial cable, and fiber-optic cable, which provide a conduit from one device to another.
Signals traveling along guided media are contained by the physical limits of the medium.
Twisted-pair and coaxial cables use metallic conductors (copper) for electrical signals.
Fiber-optic cables use light.

Twisted-Pair Cable

Consists of two conductors (usually copper) with insulated coverings twisted together.
One wire carries the signal, the other acts as a ground reference. The receiver calculates the difference between the two wires.
Interference (noise) and crosstalk can affect both wires creating unwanted signals. Twisting minimizes interference and crosstalk.
Unshielded Twisted-Pair (UTP) is the most common type, while shielded twisted-pair (STP) offers improved noise reduction.
Electronic Industries Association (EIA) categories (1-7) define cable quality with 1 being the lowest and 7 the highest and varying uses for each.

Coaxial Cable

Carries signals with higher frequencies than twisted-pair cable.
Central core conductor (solid or stranded wire, often copper) surrounded by an insulating sheath.
Encased in an outer conductor made of metal foil, braid, or a combination, which shields against noise and completes the circuit.
Protected by an outer plastic cover.
Often categorized by Radio Government (RG) ratings defining physical specifications (wire gauge, covering material).

Fiber Optic Cable

Made of glass or plastic and transmits signals in the form of light.
Light travels in a straight line unless it enters a different substance, changing direction.
Uses reflection to guide light through a core surrounded by cladding (for less dense material than the core).
Different Types: Multimode (step-index and graded-index) and Single mode
Fiber-optic cables have high bandwidth and are less susceptible to interference making them well-suited for long-distance communication, for example, backbones for cable TV networks and high-bandwidth applications.

Wireless Media

Unguided media using electromagnetic waves without physical conductors for transmission, include radio waves, microwaves, and infrared (IR).
Radio waves are omnidirectional and can transmit over long distances, useful for broadcast. Microwaves are unidirectional, useful for targeted broadcast. IR waves have a short range, but don't penetrate walls hence the preference for short-distance communication.
Omnidirectional antennas radiate signals in all directions, while unidirectional antennas (e.g. parabolic dish, horns) direct the signal in a particular direction.

Studying That Suits You

Use AI to generate personalized quizzes and flashcards to suit your learning preferences.

Description

Test your knowledge on fiber optics with this quiz covering various aspects of graded-index and single-mode fibers. Explore core diameters, cladding properties, and the physics of light propagation within fiber-optic cables. Perfect for engineering students and professionals looking to refresh their understanding of fiber optics.