Chapter 3
Physical Layer
True-False Questions
The following are possible True/False questions for tests. The statement is given and the answer
is provided in square brackets. The level of difficulty (easy, medium, and hard) and the page
number(s) relevant to the topic are also furnished.
1.
A physical circuit refers to the transmission characteristics of the connection, such as the
speed at which data is being sent through the connection.
2.
Computers produce digital data whose values are binary: 0 or 1.
3.
With modem communications, the receiving modem converts the incoming digital signal
from the telephone line into an analog signal that can be understood by the computer.
4.
Digital transmission produces more errors than analog transmission.
5.
Newer telephone circuits, built during the last decade, offer higher quality because they were
built using analog transmission.
6.
In a multipoint circuit configuration, each computer has a dedicated circuit between itself and
each of the other computers in the network.
7.
In a multipoint circuit configuration, each computer can use the circuit at the same time.
8.
In simplex transmission, the data flows in both directions at the same time
9.
A walkie-talkie is an example of half-duplex transmission.
10.
The amount of time it takes to switch between sending and receiving in half-duplex
transmission is called the propagation delay.
11.
In full-duplex transmission, two stations can send and receive simultaneously.
12.
The medium is the physical matter or substance that carries the voice or data transmission.
13.
Guided media refers to the type of media in which the message is broadcast through the air.
14.
Coaxial cable costs less and offers less shielding to electrical interference than twisted pair
cable.
15.
Fiber optic cable carries signals in traditional electrical form.
16.
Multimode fiber is capable of longer transmission distances than single mode fiber.
17.
Radio data transmission requires that each device has a radio receiver/transmitter and uses a
specific frequency.
18.
WDM is a version of FDM used in fiber-optic cables.
19.
Microwave transmissions require a line of sight between any two points.
20.
Propagation delay is negligible with satellite transmission.
21.
One form of interference with satellite transmission is called raindrop attenuation in which
the transmissions are absorbed by heavy rain.
22.
Fiber optic cable can only be used on LANs.
23.
Radio, microwave and satellite are all examples of guided media.
24.
Of all the media available, fiber optic provides the highest transmission speeds.
25.
Coding schemes are groups of bits that translate into the “alphabet” of any given system.
26.
ASCII is the least popular code for data communications.
27.
The predominant method of transferring information internally in a computer is via parallel
mode.
28.
Serial mode transmission is much faster than parallel mode transmission.
29.
Nonreturn to zero is a type of unipolar signaling
30.
With nonreturn to zero signaling, the voltage alternates between zero and a positive or
negative voltage.
31.
Ethernet, a common LAN technology, uses Manchester encoding.
32.
Manchester encoding is a special type of bipolar signaling in which the signal is changed
from high to low or from low to high in the middle of the signal.
33.
Digital transmission occurs when the signal sent over the transmission media constantly
varies among an infinite number of states.
34.
Frequency is the number of cycles per second and is expressed in Hertz.
35.
Amplitude, frequency and phase are all characteristics of a sound wave.
36.
Frequency modulation refers to the changing of the height of the sound wave.
37.
Baud rate is the number of bits transmitted per second.
38.
Signal bandwidth is the difference between the highest and lowest frequencies in a band.
39.
Data compression can increase the throughput of a communication link.
40.
A codec converts an incoming digital signal to an analog signal for transmission over an
analog network.
41.
One way to reduce quantizing errors is to increase the sampling rate of the analog signal.
42.
The “local loop” refers to the wires that run from the customer premises to the telephone
switch of the telephone company.
43.
Multiplexing increases the cost of provisioning network circuits.
44.
Frequency division multiplexing divides the circuit into a set of different time slots.
45.
Time division multiplexing is more efficient that frequency division multiplexing because the
guardbands used in the frequency division multiplexing or not needed.
46.
Statistical time division multiplexing does not require the capacity of the circuit to be equal
to the sum of the combined circuits.
47.
Wavelength division multiplexing can only used with copper cables.
48.
Digital transmission permits higher maximum transmission rates when compared to analog.
49. Multitasking means to break one high-speed physical communication circuit into
several lower-speed logical circuits so that different devices can simultaneously use it.
50. Based on the TIA/EIA 568-B structured cabling standard, the cabling that runs from
the telecommunications closet to each work area is called backbone cabling.
MULTIPLE CHOICE
The following are possible multiple-choice questions for tests. The question is posed and the
answer is provided under the choices. The level of difficulty (easy, medium, and hard) and the
page number(s) relevant to the topic is also furnished.
1.
Data is physically transmitted from one computer or terminal to another in the ________
layer.
a. physical
b. transport
c. application
d. terminal
e. data link
2.
____________ refers to the transmission characteristics of the circuit.
a. handshaking
b. virtual circuit
c. bonding
d. logical circuit
e. physical circuit
3.
Two fundamentally different types of data are:
a. DSL and ADSL
b. asymmetric and symmetric
c. Microsoft and IBM
d. digital and analog
e. local area and wide area
4.
In general, networks designed to transmit primarily computer data are likely to be ________.
a. international
b. level 1
c. numeric
d. analog
e. digital
5.
In general, older networks and local loops designed to transmit voice data are likely to be
________.
a. international
b. level 2
c. numeric
d. digital
e. analog
6.
Which of the following is not a key advantage of digital transmission?
a. It permits only low transmission rates.
b. It is more efficient.
c. It is simpler to integrate voice, video, and data on the same circuit.
d. It is more secure.
e. It produces fewer errors.
7.
_________ is the basic physical layout of the circuit.
a. point-to-point configuration
b. configuration
c. circuit configuration
d. circuit design
e. circuit plan
8.
A(n) __________ circuit is another name for a multipoint configuration.
a. analog
b. dedicated
c. point-to-point
d. shared
e. simplex
9.
Which is not true about point-to–point circuits?
a. point-to-point circuits are dedicated to the use of the two computers.
b. point-to-point circuits are more expensive than multipoint circuits.
c. point-to-point circuits are called dedicated circuits.
d. point-to-point circuits reduce the amount of cable required and use the circuit more
efficiently than multipoint circuits.
e. point-to-point circuits are used when the computers generate enough traffic to fill the
capacity of the communication circuit.
10.
Having a conversation with someone using a cellular phone is an example of _________
transmission.
a. simplex
b. full-duplex
c. half-duplex
d. analog
e. digital
11.
The ability to transmit in both directions, but only in one direction at a time is an example of
_______________ transmission.
a. simplex
b. full-duplex
c. half-duplex
d. analog
e. digital
12.
The two basic types of media are:
a. statistical and frequency
b. guided and wireless (radiated)
c. local and wide area
d. attenuator and Gaussian
e. duplexed and non-duplexed
13.
Which of the following would be considered a type of wireless media?
a. unshielded twisted pair
b. shielded twisted pair
c. coaxial cable
d. microwave
e. fiber optics
14.
The type of media usually installed on homes and businesses by the telephone company is
called ____________.
a. fiber optic cable
b. coaxial cable
c. twisted pair
d. phone cable
e. phone wire
15.
The earliest type of fiber optic systems were:
a. Graded index multimode
b. Attenuated
c. Multimode
d. Single mode
e. Step mode
16.
Another term for the weakening of a signal over distance is:
a. turnaround time
b. propagation delay
c. dispersion
d. insulation
e. attenuation
17.
___________ refers to the spreading of the signal that different parts of the signal arrive at
different times at the destination.
a. turnaround time
b. propagation delay
c. dispersion
d. insulation
e. attenuation
18.
Which of the following media can best withstand harsh environmental conditions?
a. shielded twisted pair
b. unshielded twisted pair
c. Cat 5 twisted pair
d. coaxial cable
e. fiber optic cable
19.
__________ is a line-of-sight type of wireless media.
a. coaxial cable
b. microwave
c. radio
d. twisted pair
e. fiber optic
20.
_____________ can be thought of as dividing the circuit horizontally.
a. Frequency division multiplexing
b. Statistical frequency division multiplexing
c. Statistical time division multiplexing
d. Time division multiplexing
e. Wavelength division multiplexing
21.
Microwave transmission:
a. is a type of high frequency radio communication
b. requires a clear line-of-sight path
c. is typically used for long distance data transmission
d. does not require the laying of any cable
e. all of the above
22.
______________ refers to the time it takes for a signal to travel from sender to recipient
(highly exaggerated with satellite transmission).
a. Line-of-sight effect
b. Multimode index
c. Saturation effect
d. Raindrop attenuation
e. Propagation delay
23.
Which of the following is not an important factor to consider when selecting media to be
used in a network?
a. prestige value of the type of media
b. type of network
c. cost
d. transmission distance
e. security
24.
Which of the following is the most secure wired media?
a. coaxial cable
b. unshielded twisted pair
c. shielded twisted pair
d. fiber optic cable
e. infrared