# Data Communications - Physical Layer

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This quiz is all about Physical Layer.

• 1.

### Physical layer is the lowest layer of the OSI protocol hierarchy which also means the ______________________ .

• A.

Computer

• B.

Modem

• C.

Transmission medium

• D.

Conductors

C. Transmission medium
Explanation
The physical layer is the lowest layer of the OSI protocol hierarchy, responsible for the actual transmission of data over a communication network. It deals with the physical aspects of the communication, including the transmission medium. The transmission medium refers to the physical medium through which the data is transmitted, such as cables, fiber optics, or wireless signals. Therefore, the correct answer is transmission medium.

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• 2.

### The  displacement of ____________ waves is in the direction of propagation.

• A.

Transverse

• B.

Longitudinal

• C.

Electromagnetic

• D.

Sound waves

B. Longitudinal
Explanation
Longitudinal waves are characterized by the displacement of particles in the same direction as the wave propagation. In other words, the particles move back and forth parallel to the direction of the wave. This is different from transverse waves, where the particles move perpendicular to the direction of the wave. Electromagnetic waves, such as light, are also transverse waves. Sound waves, on the other hand, are longitudinal waves because they cause particles in a medium to vibrate back and forth in the same direction as the wave travels.

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• 3.

### The displacement of ____________ waves is perpendicular to the direction of propagation

• A.

Transverse

• B.

Longitudinal

• C.

Sound waves

• D.

Surface wave of water

A. Transverse
Explanation
Transverse waves are characterized by their displacement being perpendicular to the direction of propagation. This means that as the wave moves forward, the particles of the medium through which the wave is traveling move up and down or side to side, rather than back and forth in the same direction as the wave. This is in contrast to longitudinal waves, where the displacement is parallel to the direction of propagation. Sound waves and surface waves of water can both be examples of transverse waves.

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• 4.

### A transverse wave is an  ____________ motion.

• A.

Irregular interval

• B.

Interrupted rhythm.

• C.

Oscillatory

• D.

See-saw

C. Oscillatory
Explanation
A transverse wave is an oscillatory motion. Transverse waves are characterized by particles in the medium moving perpendicular to the direction of the wave propagation. This motion is back and forth or up and down, creating a pattern of oscillations. Therefore, the correct answer is oscillatory.

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• 5.

### Electromagnetic waves are produced by the acceleration of  _________________.

• A.

An electric charge

• B.

A magnetic field

• C.

Irregular interval motion

• D.

Oscillatory motion

A. An electric charge
Explanation
Electromagnetic waves are produced when an electric charge undergoes acceleration. As the charge accelerates, it creates a changing electric field, which in turn generates a changing magnetic field. These changing electric and magnetic fields then propagate through space as electromagnetic waves. Therefore, an electric charge is the source of electromagnetic waves.

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• 6.

### Electromagnetic waves that travel along a transmission line from the source to the load are _____________ .

• A.

Reflected waves

• B.

• C.

Longitudinal waves

• D.

Incident waves

D. Incident waves
Explanation
Electromagnetic waves that travel along a transmission line from the source to the load are referred to as incident waves. Incident waves are the waves that are initially generated by the source and propagate towards the load without any reflection or distortion. They carry the information or energy from the source to the load without being affected by any reflections or interference.

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• 7.

### Electromagnetic waves that travel from the load back toward the source are called _________________.

• A.

Reflected waves.

• B.

• C.

Longitudinal waves

• D.

Incident waves

A. Reflected waves.
Explanation
When an electromagnetic wave encounters a boundary or obstacle, a portion of the wave is reflected back towards the source. These waves that travel from the load back toward the source are known as reflected waves. They carry information about the properties of the load or the boundary that caused the reflection.

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• 8.

### The distance of one cycle occurring in space is ____________.

• A.

Wave velocity

• B.

Frequency

• C.

Wavelength

• D.

Period

C. Wavelength
Explanation
The distance of one cycle occurring in space is referred to as the wavelength. It represents the distance between two consecutive points in a wave that are in the same phase. The wavelength is typically measured from crest to crest or trough to trough. It is an important parameter in understanding the characteristics and behavior of waves, such as light and sound.

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• 9.

### ___________________ is periodic and repetitive oscillations of electromagnetic wave

• A.

Wave velocity

• B.

Frequency

• C.

Wavelength

• D.

Period

B. Frequency
• 10.

### It is defined as waves travel at various speed, depending on the type of wave and the characteristics of the propagation medium

• A.

Wave velocity

• B.

Frequency

• C.

Wavelength

• D.

Period

A. Wave velocity
Explanation
Wave velocity is the correct answer because it refers to the speed at which waves travel. The velocity of a wave can vary depending on the type of wave and the characteristics of the medium through which it is propagating. This means that different waves, such as sound waves or light waves, can travel at different speeds. The velocity of a wave is typically measured in meters per second (m/s) and is calculated by dividing the distance traveled by the wave by the time it takes to travel that distance.

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• 11.

### It comprised of two or more metallic conductors separated by a nonconductive insulating material.

• A.

Open-wire

• B.

• C.

Twisted pair

• D.

Coaxial cable

A. Open-wire
Explanation
The correct answer is open-wire. Open-wire refers to a type of transmission line that consists of two or more metallic conductors separated by a nonconductive insulating material. This design allows for the transmission of electrical signals while minimizing interference and signal loss. Open-wire transmission lines were commonly used in early telecommunication systems before the advent of coaxial cables and other modern transmission technologies.

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• 12.

### It comprised of two or more metallic conductors   separated by the spacers with a continuous solid dielectric that ensures uniform spacing along the entire cable.

• A.

Open-wire

• B.

• C.

Twisted pair

• D.

Coaxial cable

Explanation
Twin-lead is the correct answer because it consists of two metallic conductors separated by spacers and has a continuous solid dielectric that ensures uniform spacing along the entire cable. This description matches the characteristics of twin-lead cables, making it the most suitable option.

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• 13.

### It is formed by twisting two insulated conductors around each other.

• A.

Open-wire

• B.

• C.

Twisted pair

• D.

Coaxial cable

C. Twisted pair
Explanation
A twisted pair is formed by twisting two insulated conductors around each other. This twisting helps to reduce electromagnetic interference and crosstalk between the two conductors. The close proximity of the twisted wires also helps to improve the overall signal quality and reduce signal loss. Twisted pairs are commonly used in telecommunications and computer networking applications.

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• 14.

### This cable consists of two copper wires where each wire is separately encapsulated in polyvinyl chloride insulation.

• A.

Shielded twisted-pair

• B.

Unshielded twisted-pair

• C.

Coaxial cable

• D.

Fiber optics

B. Unshielded twisted-pair
Explanation
This cable consists of two copper wires that are individually covered with polyvinyl chloride insulation. The term "unshielded" means that there is no additional shielding layer around the wires. The term "twisted-pair" refers to the fact that the two wires are twisted together, which helps to reduce electromagnetic interference. Therefore, the correct answer is unshielded twisted-pair.

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• 15.

### From the selection below, identify the disadvantage of using optical fiber technology.

• A.

Fiber optic transmitters and receivers are still relatively expensive compared to electrical interfaces.

• B.

Fiber optic networks operate at high speeds - up into the gigabits with large carrying capacity.

• C.

Fiber optic cables costs much less to maintain.

• D.

Fiber optics are immune to electromagnetic interference.

A. Fiber optic transmitters and receivers are still relatively expensive compared to electrical interfaces.
Explanation
The disadvantage of using optical fiber technology is that fiber optic transmitters and receivers are still relatively expensive compared to electrical interfaces. This means that the initial cost of implementing a fiber optic network can be higher than using traditional electrical interfaces.

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• 16.

### Which of the following is TRUE?

• A.

The information on the conductor are more secured than optical fiber.

• B.

Fiber optic cables sometimes produce sparks since they do have leakage current.

• C.

There are no radiated magnetic fields around optical fibers; the electromagnetic fields are confined within the fiber.

• D.

There is no loss of data when fiber optic cable is bent.

C. There are no radiated magnetic fields around optical fibers; the electromagnetic fields are confined within the fiber.
Explanation
The answer is true because optical fibers are designed to contain the electromagnetic fields within the fiber, preventing them from radiating outwards. This is one of the advantages of using fiber optic cables as they do not produce electromagnetic interference or have any impact on nearby electronic devices.

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• 17.

### Thin glass center of the fiber where the light travels is ________________.

• A.

Core

• B.

• C.

Jacket

• D.

Sheath

A. Core
Explanation
The correct answer is "core". In a fiber optic cable, the core is the thin glass center through which the light travels. It is surrounded by the cladding, which has a lower refractive index to help keep the light within the core. The jacket and sheath are protective layers that surround the cladding and core, providing additional insulation and strength to the fiber optic cable.

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• 18.

### The outer optical material surrounding the thin glass center of the fiber that reflects the light back into this thin glass is __________________.

• A.

Core

• B.

• C.

Jacket

• D.

Sheath

Explanation
The outer optical material surrounding the thin glass center of the fiber that reflects the light back into this thin glass is called cladding. Cladding is a layer with a lower refractive index than the core, which helps to confine the light within the core and prevent it from escaping. This arrangement allows for efficient transmission of light signals through the fiber optic cable.

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• 19.

### Plastic coating that protects the fiber from damage and moisture is ____________.

• A.

Core

• B.

• C.

Jacket

• D.

Sheath

C. Jacket
Explanation
The plastic coating that protects the fiber from damage and moisture is called a jacket. The jacket acts as a protective layer around the fiber, preventing any external elements from causing harm to the fiber optic cable. It provides insulation and keeps the fiber safe from physical damage and moisture, ensuring the efficient transmission of signals through the fiber.

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• 20.

### The bundles of 2 or more fiber cables are protected by the cable's outer covering, called ________________.

• A.

Core

• B.

• C.

Jacket

• D.

Sheath

D. Sheath
Explanation
The correct answer is sheath. The sheath is the outer covering of the fiber cables that protects the bundles of 2 or more fiber cables. It provides additional protection to the cables and helps prevent damage from external factors such as moisture, dust, and physical stress. The sheath is an essential component of fiber cables and plays a crucial role in maintaining the integrity and longevity of the cables.

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• 21.

### The transfer of information over a distance without the use of electrical conductors is through ___________________.

• A.

Computer

• B.

Coaxial cable

• C.

Fiber optics

• D.

Wireless transmission

D. Wireless transmission
Explanation
Wireless transmission refers to the transfer of information over a distance without the use of electrical conductors. This method utilizes electromagnetic waves to transmit signals through the air or space. Unlike computer, coaxial cable, and fiber optics, which all involve the use of physical conductors to transmit data, wireless transmission allows for the transfer of information without the need for direct physical connections.

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• 22.

### The _______________ of the telephone system can consist of digital fiber optics connecting the switching offices.

• A.

Trunks

• B.

Local loops

• C.

Switching offices

• D.

Gateway

A. Trunks
Explanation
The trunks of the telephone system refer to the pathways or lines that connect the switching offices. These trunks are often made of digital fiber optics, which provide high-speed and reliable communication between the different offices. The trunks play a crucial role in transmitting voice and data signals over long distances, ensuring efficient and effective communication within the telephone system.

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• 23.

### ____________________ of the telephone system are places where calls are moved from one trunk to another.

• A.

Trunks

• B.

Local loops

• C.

Switching offices

• D.

Gateway

C. Switching offices
Explanation
Switching offices in the telephone system are places where calls are moved from one trunk to another. These offices act as intermediaries, routing calls between different trunks to ensure that the call reaches its intended destination. They play a crucial role in connecting different parts of the telephone network and facilitating the efficient transfer of calls.

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• 24.

### In the ISO OSI network reference model, layers exist to encapsulate specific types of functionality so not to allow the divide and conquer approach to be applied to networking

• A.

The above statement is TRUE.

• B.

The above statement is FALSE.

• C.

The above statement is sometimes TRUE.

• D.

The above statement is simetimes FALSE.

B. The above statement is FALSE.
• 25.

### The Data Link Layer is a fundamental layer upon which all higher level functions in a network are based.

• A.

The above statement is TRUE.

• B.

The above statement is FALSE.

• C.

The above statement is sometimes TRUE.

• D.

The above statement is sometimes FALSE.

B. The above statement is FALSE.
Explanation
The Data Link Layer is not a fundamental layer upon which all higher level functions in a network are based. It is actually the second layer in the OSI model and is responsible for the reliable transmission of data between nodes on a network. The Network Layer is the fundamental layer upon which all higher level functions are based, as it is responsible for routing and forwarding data packets across different networks. Therefore, the statement is false.

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• 26.

### Fiber optic technology makes use of electricity to carry digital signals via optical cables.

• A.

The above statement is TRUE.

• B.

The above statement is FALSE.

• C.

The above statement is sometimes TRUE.

• D.

The above statement is sometimes FALSE.

B. The above statement is FALSE.
Explanation
The given statement is false because fiber optic technology does not make use of electricity to carry digital signals. Instead, it uses light signals to transmit data through optical cables. This technology relies on the principle of total internal reflection, where light is constantly reflected within the fiber optic cable, ensuring minimal signal loss and high data transmission speeds.

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• 27.

### Category 5 UTP is intended to use in low-speed local area networks with data rate of 16 Mbps and below.

• A.

The above statement is TRUE.

• B.

The above statement is FALSE.

• C.

The above statement is sometimes TRUE.

• D.

The above statement is sometimes FALSE.

B. The above statement is FALSE.
Explanation
Category 5 UTP is actually intended to be used in high-speed local area networks with data rates of up to 100 Mbps. Therefore, the statement that it is intended for use in low-speed networks with data rates of 16 Mbps and below is incorrect.

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• 28.

### Category 3 UTP is intended to use in high-speed local area networks with data rate of 100Mbps.

• A.

The above statement is TRUE.

• B.

The above statement is FALSE.

• C.

The above statement is sometimes TRUE.

• D.

The above statement is sometimes FALSE.

B. The above statement is FALSE.
Explanation
Category 3 UTP is not intended for use in high-speed local area networks with a data rate of 100Mbps. Category 3 UTP is designed for use in networks with a maximum data rate of 10Mbps. For higher speeds, such as 100Mbps, Category 5 or higher cables are required.

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• 29.

### The inner part of a coaxial cable is _______________.

copper core
core
Explanation
The inner part of a coaxial cable is commonly known as the copper core or simply the core. This refers to the central conductor of the cable, which is typically made of copper. The core is surrounded by an insulating layer and then a metallic shield, followed by an outer protective layer. The copper core is responsible for carrying the electrical signals through the cable, while the other layers provide insulation and protection against interference.

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• 30.

### The type of coaxial cable which uses a dielectric material to separate conductors is called __________________.

Explanation
The type of coaxial cable which uses a dielectric material to separate conductors is called "insulated coaxial cable".

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• 31.

### The type of coaxial cable which uses a solid dielectric material to separate conductors is called _______________.

Explanation
The type of coaxial cable which uses a solid dielectric material to separate conductors is called solid dielectric coaxial cable.

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• 32.

### Part of the OSI architecture that  activates, maintains, and deactivates network connections.

Physical layer
physical layer
Explanation
The physical layer of the OSI architecture is responsible for activating, maintaining, and deactivating network connections. This layer deals with the physical transmission of data over the network, including the electrical, mechanical, and functional aspects of the network interface. It ensures that the data is transmitted reliably between devices and handles tasks such as encoding, decoding, and transmitting signals. Therefore, the physical layer is the correct answer for this question.

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• 33.

### Category of transmission media with some form of conductor that provides a conduit in which electromagnetic signals are contained

guided
guided transmission media
Explanation
Guided transmission media refers to a category of transmission media that uses some form of conductor to provide a pathway for electromagnetic signals. This means that the signals are contained within the conductor, allowing for a more controlled and predictable transmission. Examples of guided transmission media include twisted-pair cables, coaxial cables, and optical fibers. These media provide a physical pathway for the signals to travel, ensuring better signal quality and less susceptibility to interference compared to unguided media.

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• 34.

### The direction of propagation in an unguided transmission medium depends on the direction in which the signal was emitted and any obstacles the signal may encounter while propagating. TRUE or FALSE?

TRUE
true
Explanation
The statement is true. In an unguided transmission medium, such as wireless communication, the direction of propagation of a signal depends on the direction in which it was emitted. Additionally, any obstacles or interference encountered by the signal while propagating can also affect its direction.

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• 35.

### Signals propagating down an unguided transmission medium are available to anyone who has a device capable of receiving them. TRUE or FALSE?

Explanation
TRUE. Signals propagating down an unguided transmission medium, such as radio waves or Wi-Fi signals, can be received by anyone with a device capable of receiving them. Unlike guided transmission mediums, which use physical cables and have limited accessibility, unguided transmission mediums allow signals to travel freely through the air or space, making them accessible to anyone within range. This is why unguided transmission mediums are commonly used for broadcasting and wireless communication.

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• 36.

### Transmission media should be transparent to data with the sole purpose of transporting bits among computers, computer networks and other computer equipment. TRUE or FALSE?

TRUE
true
Explanation
Transmission media refers to the physical means through which data is transmitted, such as cables or wireless signals. These media should ideally be transparent to data, meaning they should not alter or modify the data being transmitted. Their sole purpose is to transport the bits of data accurately and efficiently between computers, networks, and other equipment. Therefore, the statement that transmission media should be transparent to data is true.

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• 37.

### Transmission medium is simply the path between a transmitter and a receiver in a communications system. TRUE or FALSE?

TRUE
true
Explanation
The statement is true. The transmission medium refers to the physical pathway through which signals are transmitted from a transmitter to a receiver in a communication system. It can be a wired medium like copper cables or fiber optics, or a wireless medium like radio waves or satellite signals. The choice of transmission medium depends on factors like distance, data rate, cost, and environmental conditions.

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• 38.

### ______________________  is a transmission line is a metallic conductor system used to transfer electrical energy from one point to another using electrical current flow.

metallic cable
metallic
Explanation
The correct answer is "metallic cable." A metallic cable is a type of transmission line that is made of a metallic conductor. It is used to transfer electrical energy from one point to another by allowing electrical current to flow through it. This type of cable is commonly used in various applications to transmit electricity efficiently and safely.

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• 39.

### Transmission lines can be used to propagate only dc or low-frequency ac signals. TRUE or FALSE?

FALSE
false
Explanation
Transmission lines can be used to propagate both DC and high-frequency AC signals. This is because transmission lines are designed to transmit electrical signals over long distances with minimal distortion. While DC signals do not have a frequency, transmission lines can still transmit them effectively. Additionally, transmission lines can also propagate high-frequency AC signals, which are commonly used in telecommunications and power transmission systems. Therefore, the statement that transmission lines can only be used to propagate DC or low-frequency AC signals is false.

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• 40.

### An example of a transverse wave is surface wave of water. TRUE or FALSE?

FALSE
false
Explanation
An example of a transverse wave is the surface wave of water. This statement is false. The surface wave of water is actually an example of a type of wave called a "capillary wave", which is a combination of both longitudinal and transverse wave motion. Transverse waves are characterized by the particles of the medium oscillating perpendicular to the direction of wave propagation, while longitudinal waves have particles oscillating parallel to the direction of wave propagation.

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• 41.

### The spatial relationship between the electric and magnetic field in the electromagnetic wave where the E and H are perpendicular to each other at all points is called _______________.

• A.

Incident waves

• B.

Reflected waves

• C.

• D.

Vacuum

Explanation
The spatial relationship between the electric and magnetic field in an electromagnetic wave where they are perpendicular to each other at all points is called "space quadrature". This means that the electric field vector is perpendicular to the magnetic field vector, forming a right angle. This relationship is a fundamental characteristic of electromagnetic waves and is essential for their propagation through space.

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• 42.

### In the very low frequency bands, radio waves follow the atmospheric layers of the earth. TRUE or FALSE?

FALSE
false
Explanation
In the very low frequency bands, radio waves do not follow the atmospheric layers of the earth. They are able to penetrate the earth's surface and travel long distances, even beyond the line of sight. Therefore, the statement that radio waves in the very low frequency bands follow the atmospheric layers of the earth is false.

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• 43.

### A satellite that appears stationary with respect to a fixed point on the rotating Earth.

• A.

Geostationary satellite

• B.

Medium-Earth Orbit Satellite

• C.

Low-Earth Orbit Satellite

A. Geostationary satellite
Explanation
A geostationary satellite is a satellite that appears stationary with respect to a fixed point on the rotating Earth. This means that it orbits the Earth at the same rotational speed as the Earth itself, resulting in the satellite always remaining above the same point on the Earth's surface. This type of satellite is commonly used for telecommunications, weather monitoring, and broadcasting, as it allows for continuous coverage of a specific area on the Earth's surface.

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• 44.

### A satellite designed to help facilitate high-speed telephone signals.

• A.

Geostationary satellite

• B.

Medium-Earth Orbit Satellite

• C.

Low-Earth Orbit Satellite

B. Medium-Earth Orbit Satellite
Explanation
A medium-Earth orbit satellite is the most suitable option for facilitating high-speed telephone signals. Geostationary satellites are placed in a fixed position above the equator, which limits their coverage to specific regions. Low-Earth orbit satellites, on the other hand, are closer to the Earth's surface and are primarily used for applications such as remote sensing and global positioning systems. Therefore, a medium-Earth orbit satellite, which orbits between the geostationary and low-Earth orbits, provides a balance between coverage and signal quality, making it ideal for high-speed telephone signals.

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• 45.

### Satellites that orbit so close to Earth.

• A.

Geostationary satellite

• B.

Medium-Earth Orbit Satellite

• C.

Low-Earth Orbit Satellite

C. Low-Earth Orbit Satellite
Explanation
Low-Earth Orbit Satellites are the correct answer because they orbit at a relatively close distance to Earth compared to geostationary and medium-Earth orbit satellites. These satellites are typically located between 180 to 2,000 kilometers above the Earth's surface. They have a faster orbital speed, which allows them to complete orbits in a shorter period of time. This proximity to Earth enables low-Earth orbit satellites to provide faster data transmission, lower latency, and better coverage for applications such as communication, weather monitoring, and Earth observation.

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• 46.

### The band of frequencies that is too high to be seen by the human eye.

infrared
Explanation
Infrared refers to the band of frequencies that is too high to be seen by the human eye. Infrared radiation has longer wavelengths than visible light, making it invisible to us. However, it can be detected and utilized for various purposes, such as in thermal imaging, remote controls, and communication systems. Infrared radiation is often associated with heat, as objects emit infrared radiation based on their temperature.

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• 47.

### The band of frequencies to which the human eye will respond.

visible
Explanation
The term "visible" refers to the band of frequencies that the human eye is able to detect and respond to. This includes the range of colors that are perceivable by humans, typically ranging from red to violet. The human eye is not sensitive to frequencies outside of this visible spectrum, such as infrared or ultraviolet. Therefore, the correct answer is "visible" because it accurately describes the specific range of frequencies that the human eye can see.

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• 48.

### The band of frequencies that are too low to be seen by the human eye.

Explanation
The band of frequencies that are too low to be seen by the human eye refers to the range of electromagnetic waves known as infrared. Infrared waves have longer wavelengths than visible light, making them invisible to the naked eye. However, they can be detected and utilized by certain devices, such as infrared cameras and sensors. Infrared radiation is commonly used in various applications, including night vision technology, remote controls, and thermal imaging.

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• Mar 22, 2023
Quiz Edited by
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• Feb 04, 2009
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