CBSE Class 9 Foundation of Information Technology NCERT Solutions: Chapter 4 - Communication Technology

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NCERT Solutions PDF Class 9 PDF

This chapter provides essential NCERT Solutions for Class 9 Foundation of Information Technology, focusing on Chapter 4: Communication Technology. Students will explore fundamental concepts of computer networks, understanding what constitutes a network and its basic components. The solutions explain the role and importance of communication channels in transmitting data, differentiating between guided and unguided media. Key network types like LAN, MAN, and WAN are introduced, along with the specific cable types used in LANs. The chapter also clarifies why the Internet is termed a 'network of networks' and the technical reasons behind the design of twisted pair cables. These solutions are designed to help students grasp these core concepts effectively for their exams.

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Quick info

BoardCBSE
ClassClass 9
SubjectFoundation of Information Technology
Session2026
LanguageEnglish
TypeNCERT Solutions
ChapterChapter 4

Chapter summary

Chapter 4 of the Foundation of Information Technology syllabus for Class 9 covers the basics of Communication Technology. The NCERT Solutions provided here explain key terms like computer networks, the definition of communication, and examples of communication technologies. It details the components of a computer network, the significance of communication channels, and categorizes networks into LAN, MAN, and WAN. The solutions also touch upon cable types for LANs, the nature of the Internet as a network of networks, and the distinction between guided and unguided transmission, including the purpose of twisting wires in twisted pair cables.

Learning outcomes

  • Understand the definition and purpose of a computer network.
  • Identify the essential components of a computer network.
  • Explain the role and types of communication channels.
  • Differentiate between various types of computer networks (LAN, MAN, WAN).
  • Recognize the technologies used for network connections.
  • Comprehend the structure of the Internet as a network of networks.

Topics covered

Paper topics

  • Computer Network Definition
  • Communication Definition
  • Examples of Communication Technology
  • Components of a Computer Network
  • Communication Channel Importance
  • Types of Computer Networks (LAN, MAN, WAN)
  • LAN Cable Types
  • Internet as a Network of Networks
  • Guided vs. Unguided Transmission
  • Twisted Pair Cable Design

Important topics

  • Computer Network Components
  • Types of Computer Networks (LAN, MAN, WAN)
  • Role of Communication Channel
  • Guided vs. Unguided Transmission
  • Internet as a Network of Networks

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Questions and Solutions

Question 1.

Name the term defined by the following statement: "A group of computers connected to each other by a link."
Solution: The term defined by the statement "A group of computers connected to each other by a link" is a Computer Network. This interconnection allows computers to share data, resources, and communicate with each other.

Question 2.

Two people, one knowing only English and the other knowing only Chinese, are talking to each other. Can we call it a communication?
Solution: No, this cannot be called effective communication. Communication requires a meaningful exchange of information where both parties can understand each other. Since one person only knows English and the other only knows Chinese, there is a language barrier, preventing a successful and meaningful exchange of ideas.

Question 3.

Give a few examples of communication technology.
Solution: Several technologies facilitate communication. Some common examples include:
  • Telephones
  • Mobile phones
  • Fax machines
  • The Internet
  • Email
  • Video conferencing systems
These technologies enable the transmission of information across distances.

Question 4.

Write down the components of a computer network established between the two offices of a company located across different cities.
Solution: Establishing a computer network between two offices in different cities involves several key components to ensure data communication. These components are:
  1. Sender: The device or computer that initiates the transmission of data.
  2. Data communication device at sender's end: This could be a modem or router at the sending office that prepares the data for transmission over the communication channel.
  3. Communication channel: This is the medium through which data travels. For offices across cities, this would typically be telephone lines, leased lines, or satellite links.
  4. Data communication device at receiver's end: Similar to the sender's end, this device (e.g., modem, router) at the receiving office receives the data from the channel and makes it understandable for the receiver.
  5. Receiver: The device or computer at the destination office that receives the transmitted data.
These components work together to facilitate the exchange of information between the two geographically separated offices.

Question 5.

What is the importance of a communication channel?
Solution: The communication channel is a vital component of any network because it serves as the physical or wireless pathway responsible for carrying data in the form of signals from the sender to the receiver. Without a communication channel, data cannot be transmitted between different points in a network.

Question 6.

List down the types of computer networks.
Solution: Computer networks are primarily classified based on their geographical area of coverage. The three main types are:
  1. Local Area Network (LAN): Connects devices within a small geographical area, like a single building or office.
  2. Metropolitan Area Network (MAN): Spans a larger area than a LAN, typically covering a city or a large campus.
  3. Wide Area Network (WAN): Covers a broad geographical area, often connecting multiple LANs or MANs across countries or continents. The Internet is an example of a WAN.

Question 7.

Which cable networks are used for LAN connections?
Solution: For establishing Local Area Network (LAN) connections, two primary types of cables are commonly used:
  1. Twisted pair cables: These are the most common and cost-effective cables used in Ethernet LANs.
  2. Fibre optic cables: These cables use light pulses to transmit data and offer higher bandwidth and longer transmission distances compared to twisted pair cables, making them suitable for high-speed networks.

Question 8.

Why is the Internet called a network of networks?
Solution: The Internet is referred to as a "network of networks" because it is not a single entity but rather a vast, interconnected global system. It comprises millions of smaller, independent networks—ranging from private networks within organizations to public networks run by Internet Service Providers (ISPs)—all linked together using standardized communication protocols (like TCP/IP) to exchange information seamlessly.

Question 9.

Give one basic difference between guided and unguided transmission channels.
Solution: The fundamental difference between guided and unguided transmission channels lies in how data is transmitted:
  • Guided Transmission: In guided media, data travels through physical cables or wires that confine the signal, such as twisted pair cables, coaxial cables, or fibre optic cables.
  • Unguided Transmission: In unguided media, data travels wirelessly through the air or space in the form of electromagnetic waves, without the need for physical cables. Examples include radio waves, microwaves, and infrared signals.

Question 10.

Why are wires in a twisted pair cable twisted around each other?
Solution: The wires in a twisted pair cable are twisted around each other primarily to reduce electromagnetic interference and noise from external sources, as well as to minimize crosstalk between adjacent pairs of wires. This twisting helps to cancel out the effects of interference, ensuring a more reliable and stable data transmission.

Common mistakes

  • Confusing communication with mere data transmission without meaning.
  • Not listing all essential components of a computer network.
  • Failing to distinguish between guided and unguided transmission media.
  • Incomplete understanding of the geographical scope of LAN, MAN, and WAN.

Revision tips

  • Review the definitions of key terms like 'computer network' and 'communication'.
  • Memorize the components required for establishing a computer network.
  • Understand the differences and examples of LAN, MAN, and WAN.
  • Pay attention to the purpose of specific cable designs like twisted pair.

Practice MCQs

Q1. What is a group of computers connected to each other called?

Q2. Which of the following is NOT a component of a computer network?

Q3. What is the primary function of a communication channel?

Q4. Which type of network typically covers the smallest geographical area?

Q5. Why are wires in a twisted pair cable twisted?

Frequently asked questions

What is a computer network according to Chapter 4?

A computer network is defined as a group of computers that are connected to each other by a link, enabling them to share information and resources.

What are the main types of computer networks discussed?

The main types of computer networks discussed are Local Area Network (LAN), Metropolitan Area Network (MAN), and Wide Area Network (WAN), categorized by their geographical coverage.

Why is the Internet called a 'network of networks'?

The Internet is called a 'network of networks' because it connects numerous large and diverse networks together, forming a single, massive global network.

What is the purpose of twisting wires in a twisted pair cable?

The wires in a twisted pair cable are twisted to protect the signal from external noise and interference, a phenomenon known as crosstalk, thereby ensuring clearer data transmission.

What is the importance of a communication channel?

A communication channel is crucial as it serves as the pathway for data to travel in the form of signals from the sender to the receiver.

Important links

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