Class – 8th
Subject : Computer
L- 9 Communication Technology
Book Exercise
A. Choose the Correct Answer.
1. Elements of Communication system.
a) Sender
b) Medium
c) Receiver
d) All of these
2. The Transmission media can be classified into categories.
a) 2
b) 4
c) 1
d) 3
3. The length of cable extends beyond meters.
a) 500
b) 100
c) 250
d) 350
4. Radio Wave within the frequency range between.
a) 30 KHz to 300 GHz
b) 32 KHz to 350 GHz
c) 25 KHz to 250 GHz
d) 35 KHz to 400GHz
5. Microwave within the frequency range between.
a) 350 MHz to 350 GHz
b) 300MHZ to 300GHz
c) 250 MHz to 250 GHz
d) 150 MHz to 150 GHz
B. Fill in the blanks:-
1. Twisted Pair Cable the rate of data transfer is approx 9600 bit per second (9600 baud).
2. The length of cable extends beyond 100
meters.
3. PC the full form Personal Computer.
4. The rate of transmitting microwave signals is about 300 MHz and 300 GHz. form a transmitter.
5. Wi-Fi system means wireless data transmission.
C. Name the following
1. Three types of
cables used in data transmission
Ans: a Twisted Pair Cable
b Coaxial Cable
c Optical fiber Cable
2. Three types of
communication protocols.
Ans
: There are various types of protocols that support a major and compassionate
role in communicating with different devices across the network. These are:
1.
Transmission Control Protocol (TCP)
2.
Internet Protocol (IP)
3.
User Datagram Protocol (UDP)
4.
Post office Protocol (POP)
5.
Simple mail transport Protocol (SMTP)
6.
File Transfer Protocol (FTP)
7.
Hyper Text Transfer Protocol (HTTP)
8.
Hyper Text Transfer Protocol Secure (HTTPS)
9.
Telnet
10.
Gopher
3. Three types of wireless transmission.
Ans: 1.
Radio Wave
2.
Microwave
3.
Communication Satellite
4.
Wi- Fi System
D. Questions answer.
1. What do you
understand by communication system? Name three basic elements of a
communication system.
Ans: Communication system helps transfer data from one point to
another using resources. The data may be analogous or digital in nature.
In
any communication process three elements are essentially needed. They are:
1. Sender :- it creates the messages
to be transmitted.
2. Medium :- it carries the
transmitted messages to the destination.
3. Receiver :- it
receives the messages from the sources.
2. What is a
Communication satellite? How is it useful in the field of data communication?
Ans: The communication satellite is basically a microwave relay
station placed in outer space. The satellite is launched by rockets above the
equator with an orbit speed that matches the earth's rotation.
The
main advantage of satellite
communication
is that it is a single microwave relay station, visible from a very large area.
A signal sent to a satellite is broadcast to al receivers within the satellite
range
3. Write short notes
on:-
1. Twisted Pair
Cable
Ans: This cable is commonly used in local telephone communication
for short distance (up to 1 km) data transmission. Generally, it is made of
copper and a pair of wires is twisted to reduce the interference by adjacent
wires. The cable is used to connect terminals to the main computer, if they are
placed at a short distance. The rate of data transfer
is approx. 9600 bits per second (9600 baud).
2. Coaxial cable
Ans: Coax, short for coaxial, is a type of cable used to
transmit data, the internet, video and voice communications. A coax cable is made up of an aluminum and copper shield
with an outer plastic jacket (see below) with the dielectric insulator helping
to minimize signal loss
3. Wi-Fi System
Ans: Wi- Fi stands for wireless fidelity that allows wireless data
transmission.
Unlike mobile phones, any standard Wi- Fi device will anywhere in the world to
transfer data through computers and mobile phones. Today, W- Fi is widely used
in offices, hospitals, airports, corporate and university campuses worldwide. A
Wi- Fi enabled device such a a PC, video game console, mobile phone or MP3
player can connect to the internet when it is within the range of a wireless
network connected to the internet .
4. Optical fiber Cable
Ans: It is one of the latest technologies in the field of data
transmission
Which is an alternative to satellite communication. It can transmit 50,000 voice messages
simultaneously by means of advanced laser technology.
4. Explain the
following.
1. Elements of
Communications System
Ans: In any communication process three elements are essentially
needed. They are:
1. Sender :- it creates the messages
to be transmitted.
2. Medium :- it carries the
transmitted messages to the destination.
3. Receiver :- it
receives the messages from the sources
2. Radio Wave
Ans: Radio waves are theelectromagnetic waves within the
frequency
range between 30 KHz to 300 GHz. These waves have lowest energy but can travel
through the atmosphere. Communication is done through wireless transmission
where signals are converted into sound waves by the receiver.
5. Give two
differences between Microwave and communication
Satellite.
Ans:
|
Microwave
|
communication
Satellite
|
|
Microwave are also electromagnetic
waves with
frequency between 300 MHz and 300 GHz. They have a high
frequency and high energy. They pass through the atmosphere but are affected
by wave effects like reflection and refraction.
The transmitters and receives of
microwave systems are mounted on very high towers so that they are in a
line-ofsight
|
The communication satellite is basically a microwave relay
station placed in outer space. The satellite is launched by rockets above the
equator with an orbit speed that
matches the earth's rotation. Relative to earth, it is
stationary and always stays over
the same point on the ground. It allow a ground station to aim
its antenna at a fixed point in the sky.
|
