L- 9 Communication Technology / Class 8th Computer

 

Class – 8^th

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.