ICT

 

INFORMATION AND

COMMUNICATION TECHNOLOGY

Science and Technology - Grade 10 | Chapter 13

✎ Notebook guide ·       Read objectives first, then learn definitions, diagrams and comparison tables. ·       This chapter asks concept questions about analogue/digital signals, digital communication, broadband, online reputation and digital well-being. ·       Practice unit conversions such as bit, nibble, byte, KB, MB, GB and TB. ·       For long answers, write definition -> explanation -> example -> conclusion.

 

✦ Contents

1.     Learning objectives

2.     Warm-up observations and concept answers

3.     Key definitions

4.     Formula corner and memory unit bank

5.     Full notes

6.     Important sketch diagrams and picture notes

7.     Numericals and practical calculations

8.     Comparison tables

9.     Activity and project summaries

10.  Exercise answer key and model answers

11.  Questions for brainstorming

12.  Quick revision and exam tips

✦ 1. Learning Objectives

·       Define signal, analogue signal, digital signal, bit, byte, binary digit, digital native, digital citizen, netizen, digital citizenship, online reputation and digital well-being.

·       Explain why antenna TV has lower audio-visual quality than cable TV, Dish TV and Internet TV.

·       Describe the need for ADC and DAC in broadcasting and digital devices.

·       Differentiate between analogue and digital signals using nature, graph, values, converters and examples.

·       Explain how binary digits 0 and 1 represent digital signals and data in computer memory.

·       Convert between bit, nibble, byte, KB, MB, GB and TB.

·       Explain signal transmission and list components of a digital communication system in correct order.

·       Compare analogue communication and digital communication.

·       Differentiate baseband transmission and broadband transmission with examples.

·       Write advantages of digital transmission and explain how digital technology has developed ICT.

·       List digital technologies used in daily life and evaluate their positive and negative effects.

·       Explain characteristics of a good netizen and importance of digital reputation management.

·       Describe digital well-being and write precautions for balanced digital health.

·       Explain how audio and audio-visual materials are recorded, edited, trimmed, joined and exported.

✦ 2. Warm-up Observations and Concept Answers

Observation / Question	Notebook Answer
Why is antenna TV usually poorer in quality?	Waves from the transmitter lose energy while travelling through air. Therefore less p.d. is produced on the antenna and the modulated signal becomes weak.
Why is Dish TV better than old antenna TV?	Dish TV receives digital signals from a satellite, so the information is clearer and less affected by ordinary noise.
Why does TV need analogue-digital conversion?	Sound and light are analogue in nature, but digital devices process data in 0 and 1. Therefore analogue signals must be converted into digital signals and later back into analogue output.
Why is a digital signal represented by 0 and 1?	Digital signal uses two fixed levels: low/off is 0 and high/on is 1.
Why is digital communication more reliable?	Noise, distortion, cross-talk and error are lower; coding, compression and error correction can be used.
Why should we manage online reputation?	Posts, comments, profile details and privacy settings create a permanent impression about a person or organization online.
Why is digital well-being important?	Excess screen time may cause health, emotional and social problems; balanced online and offline habits reduce these risks.

✦ 3. Key Definitions

Term	Meaning
Signal	A physical quantity that changes with time and carries information, such as sound, voltage, light intensity or electromagnetic waves.
Analogue signal	A signal that represents a continuously changing physical quantity. It changes smoothly with time and is often shown by a sine wave.
Digital signal	A signal that represents a physical quantity in separate fixed levels, commonly two levels: 0 and 1.
High signal	The ON/high-voltage state of a digital signal. In the activity, 5 V across the bulb represents high signal or 1.
Low signal	The OFF/zero-voltage state of a digital signal. In the activity, 0 V across the bulb represents low signal or 0.
Binary digit / Bit	The smallest form of computer data. It is a single binary digit and can be either 0 or 1.
Nibble	A group of 4 bits.
Byte	A group of 8 bits, or 2 nibbles, that works as a single unit of data in a computer.
Computer memory	The storage system of a computer that stores data such as text, graphics, audio and video.
ADC	Analogue to Digital Converter; a device/circuit that changes analogue signal into digital signal.
DAC	Digital to Analogue Converter; a device/circuit that changes digital signal into analogue signal.
Signal transmission	The process of transferring information through a medium or channel using signals such as sound, voltage or electromagnetic waves.
Source	The origin of the information to be transmitted, for example sound waves from a speaker or microphone input.
Input transducer	A device that converts a physical signal into an electrical signal; for example, a microphone converts sound into electricity.
Encoder	A component that compresses or represents data using a minimum number of bits for efficient use of bandwidth.
Modulator	A component that combines data with a carrier signal and prepares it for transmission through a channel.
Channel / Medium	The path through which signals travel from transmitter to receiver, such as cable, air, optical fibre or radio channel.
Demodulator	The receiver-side component that separates the information signal from the modulated carrier signal.
Decoder	A component that re-digitalizes and reconstructs the received signal, reducing possible errors.
Output transducer	A device that converts electrical output into a physical signal; for example, a loudspeaker converts current into sound.
Analogue communication	Communication in which data are sent between transmitter and receiver using analogue signals.
Digital communication	Communication in which signals are digitized, transmitted, and then converted back into analogue output.
Baseband transmission	Transmission of digital signals through a channel without converting them into analogue signals; useful for short distance.
Broadband transmission	Transmission of digital data after converting digital signals into analogue carrier signals; useful for high-speed and long-distance communication.
Bandwidth	The available range of frequencies of a channel used for data transmission.
Digital media	Electronic media and devices used to create, store, share and receive information digitally.
Digital technology	Technology that uses digital data and devices in communication, education, health, entertainment, finance and other fields.
Digital native / Digital citizen	A person who actively participates in digital technology and online environments.
Netizen	A citizen of the internet: a person who actively uses and engages in the internet.
Digital citizenship	The responsible citizenship of a netizen in the virtual world of the internet.
Online reputation	The public impression and credibility of a person or organization formed by online profile, posts, comments, shares, privacy and digital behavior.
Digital well-being	A healthy balance of mental, physical, social and emotional life by managing online and offline activities properly.
Video editing	The process of cutting unnecessary video parts, combining clips and exporting a complete video file.
Audio editing	Editing sound files such as MP3, WAV and WMA by cutting, joining or improving recorded audio.

✦ 4. Formula Corner and Memory Unit Bank

Sketch 4: Memory unit ladder used for bit-byte conversion numericals.

Relation	Equivalent	Use / Meaning
1 bit	one binary digit: 0 or 1	smallest data unit
4 bits	1 nibble	half byte
8 bits / 2 nibbles	1 byte	one unit of computer data
1024 bytes	1 kilobyte (KB)	small text files
1024 KB	1 megabyte (MB)	images, documents, short audio
1024 MB	1 gigabyte (GB)	videos, apps, storage
1024 GB	1 terabyte (TB)	large storage devices

✎ Binary combinations ·       With 1 binary digit: 2 possible values: 0 and 1. ·       With 2 binary digits: 4 combinations: 00, 01, 10 and 11. ·       With 3 binary digits: 8 combinations: 000, 001, 010, 011, 100, 101, 110 and 111. ·       General idea: each extra bit doubles the number of possible combinations.

 

✦ 5. Full Notes

5.1 Television Broadcasting and Signals

Information and communication technology begins with the idea of sending information from one place to another. In television broadcasting, the information may be picture, sound and related data. Old antenna-powered television receives waves that travel through air. As the waves travel, they lose energy to the surroundings. Because of this, the potential difference generated on the antenna becomes weak and the modulated signal becomes unclear. Therefore, antenna TV usually has poorer audio-visual quality than cable TV, Dish TV and internet-based TV.

In cable TV, the signal travels through a wire as a modulated signal. Internal circuits of the television convert received signals into digital signals so that audio-visual content can be reproduced. If a computer is used as a television by connecting a cable, a cable modem is required. Dish TV receives digital signals from satellite and has expanded television service to many places.

Sketch 1 repeated: comparison of antenna, cable and Dish/Internet TV signal paths.

5.2 Analogue-Digital Conversion

Human senses experience sound and light as continuously changing signals. These are analogue in nature. Digital devices, however, store and process information using digital data. Therefore, for broadcasting and digital media, analogue signals often need to be converted into digital signals and later digital signals need to be converted back into analogue signals. This is why ADC and DAC are important in modern ICT devices.

Analogue to Digital Converter (ADC) changes an analogue signal into digital form. Digital to Analogue Converter (DAC) changes the digital signal into analogue output so that it can be heard by the ear or seen by the eye. For example, a temperature sensor may use ADC, while music playback from a computer uses DAC to produce sound through a speaker.

Sketch 2: Analogue signal is converted into binary digital data and converted back into physical output.

5.3 Digital Signal and Analogue Signal

A signal is any physical quantity that changes with time. In a simple digital signal activity, a bulb connected to a 5 V source can represent two fixed conditions. When the switch is ON, the p.d. across the bulb is 5 V, so it is a high signal or 1. When the switch is OFF, the p.d. becomes 0 V, so it is a low signal or 0. A graph of this signal looks like a square wave because it changes between two fixed values.

If the switch were not turned off and the voltage across the bulb changed continuously, the graph would show a smooth rise and fall. This is an analogue signal. Analogue signal is represented by a sine wave, while digital signal is represented by a square wave or binary sequence.

Sketch 3: Digital high/low states using switch, bulb and voltage-time graph.

5.4 Binary System and Computer Memory

Digital signals are represented by the two digits 0 and 1. This is called the binary system. A single binary digit is called a bit. The combination of bits represents different data. A computer stores data in memory in many formats such as text, graphics, audio and video. The capacity of computer memory is measured using units such as bit, byte, kilobyte, megabyte, gigabyte and terabyte.

The important conversion facts are: 4 bits make 1 nibble; 8 bits or 2 nibbles make 1 byte; 1024 bytes make 1 kilobyte; 1024 kilobytes make 1 megabyte; 1024 megabytes make 1 gigabyte; and 1024 gigabytes make 1 terabyte. These conversions are useful for exam numericals and practical file-size calculations.

5.5 Signal Transmission

In daily life, we communicate using sound. Sound is an analogue signal because it varies continuously. In a landline phone, analogue communication signals may be sent through wires. The process of sending a signal through a medium or channel is called signal transmission. Communication can also occur through potential differences, electromagnetic waves and optical signals.

Traditional communication often used analogue transmission, such as radio broadcast using medium waves and short waves. Such signals may be affected by atmospheric effects, mixing of other waves and signal distortion. Digitalizing analogue signals makes the signal clearer, more distinct and more secure. In a digital system, data can be stored, transmitted and recreated using groups of 0 and 1, and data processing becomes easier with lower probability of error.

5.6 Components of a Digital Communication System

A digital communication system has several stages. First, the source produces a signal. The input transducer changes the physical signal into an electrical signal. The encoder compresses or represents the data in bits. The modulator prepares the signal for transmission by using a carrier signal. The channel gives the path for the signal. On the receiver side, the demodulator removes the carrier, the decoder reconstructs the digital data, the output transducer changes electrical signal into physical output, and the output signal is received by the user.

Sketch 5: Block diagram of digital signal transmission from source to output signal.

Component	Function
Source	Original information such as sound waves, image or data.
Input transducer	Converts physical signal into electrical signal; microphone is an example.
Encoder	Compresses data to minimum bits and uses bandwidth efficiently.
Modulator	Modulates data with a carrier and sends it toward the channel.
Channel	Medium/path such as wire, air, radio channel or optical fibre.
Demodulator	First receiver-side process; demodulates the received signal.
Decoder	Reconstructs/re-digitizes the signal and removes possible errors.
Output transducer	Converts electrical output into physical output, such as loudspeaker sound.
Output signal	Final message received after transmission.

5.7 Analogue and Digital Communication

In analogue communication, data are sent between transmitter and receiver using analogue signals. These signals can be highly affected by external influences. Coding is not possible in ordinary analogue communication, but it needs comparatively small bandwidth. In digital communication, analogue signals are first digitized, transmitted, and then converted back into analogue output. Digital communication is less affected by external noise, allows coding and security, but generally needs larger bandwidth.

5.8 Baseband and Broadband Transmission

Baseband transmission means transmission of digital signals through a channel without converting digital signals into analogue signals. The sending and receiving process happens in the same channel. It is suitable for short-distance transmission. For example, sending data from one computer to another by connecting them with a cable is baseband transmission.

Broadband transmission means transmission of digital signals through a channel after converting them into analogue signals. It requires modulation. Broadband transmission is used for high-speed internet and long-distance transmission. It may transmit signals as optical waves or electromagnetic waves in different frequency ranges. In broadband, separate channels or separate cables may be used for sending and receiving signals.

Sketch 6: Baseband sends digital bits directly; broadband uses carrier modulation.

5.9 Advantages of Digital Transmission

·       Deterioration and noise effects are very low in digital signals.

·       Digital transmission circuits are more reliable.

·       Digital circuits are cheaper and easier to design than many analogue circuits.

·       There is less possibility of signal overlap and cross-talk.

·       Properties of digital signals remain stable in normal conditions.

·       Information security can be maintained by encoding and compression.

·       Error-detecting and error-correcting codes reduce transmission errors.

5.10 Influence of Digital Technology on ICT Development

The development of digital technology has improved the quality and spread of information and communication technology. Modern telecommunication, internet facilities, digital media and digital TV have become possible due to digital technology. Digital telecommunication allows fast communication and enables many telephone calls to be transmitted through a single channel or bandwidth. Digital media allows creating, sharing, watching news and transmitting online information through electronic devices.

Digital TV uses modern digital technology and high-definition systems. Different types of digital television such as satellite, cable and internet-based services have expanded the reach of information and entertainment.

5.11 Digital Technologies Used in Daily Life

Digital technologies are now used in education, health, finance, entertainment, travel, communication, business and public services. Examples include infrared and digital thermometers, calculator, online newspaper, digital wallet, online library, speedometer, digital camera, smartwatch and digital calendar. These devices and services make work faster and easier, but careless use can also create problems.

Sketch 7: Common digital devices and services used in daily life.

5.12 Positive Effects of Digital Technology

·       Digital library gives access to digital textbooks, reference materials and learning resources.

·       Online newspapers can be read easily using internet and smartphones.

·       Digital payment reduces the need to carry cash and can be used for shopping, taxes, bus tickets and plane tickets.

·       Online business helps promote and sell products through the internet.

·       Social networks help people express opinions and connect even when physically far away.

·       Digital entertainment provides games, music, videos and other applications.

5.13 Negative Effects of Digital Technology

·       Excess online time can change social behavior and reduce real-world interaction.

·       Cybercrime through social media can affect personal, family and social life.

·       Damage to reputation can create mental stress.

·       Excessive digital material may reduce use of physical materials and business opportunities.

·       Lack of physical exercise in children may cause obesity and weakness.

·       Violent digital games can affect mental health and social well-being.

·       Misuse of digital technology can harm people through cybercrime and antisocial activities.

5.14 Digital Citizenship and Good Netizen

A netizen is a citizen of the internet. Digital citizenship refers to responsible citizenship in the virtual world. The concept of digital citizenship helps improve the internet world. Digital technology connects people through telephone, internet calls, social networks and many communication channels. This has developed the idea of a global village.

A good netizen follows internet etiquette. Online communication should use polite and civilized language. Respect for oneself and others should be shown in emails, comments, public posts and social media discussions. Anything posted online can become permanent. Intellectual property belongs to its creator, so the source should be cited when using someone else's material.

Sketch 8: Good netizen habits and online reputation around the global internet community.

5.15 Online Reputation and Digital Reputation Management

Online reputation is connected to practical life reputation. A person should use real name, real photo and reliable public details on an online profile. This increases authenticity and reliability. Using the same username on social media profiles helps identify the same person. Posts, comments and shares show a person's knowledge, expertise, attitude and behavior.

Online reputation also applies to organizations. Information published on an organization's website and social media pages is official. Followers, comments and public responses affect credibility. Institutional reputation can be managed by being present on important platforms and by resolving comments and complaints on time. Poor privacy settings can cause password theft or posting of harmful content, so internet security is important.

5.16 Digital Well-being

Using online technology for a long time without balance can harm health. It may cause obesity, insomnia, eye/vision problems and mental stress. Unregulated internet use may also lead to depression, anxiety, dishonesty, low self-esteem, social isolation, loneliness and aggressiveness. Digital well-being means being healthy mentally, physically, socially and emotionally by balancing online and offline activities.

Digital well-being can be improved by separating screen time, setting time limits for social media, turning off notifications while working, taking breaks, doing physical exercise and using digital wellbeing applications. Such applications can display screen time, allow app timers and help reduce unnecessary use of digital devices.

Sketch 9: Digital well-being balances mental, physical, social and emotional health.

5.17 Making Audio and Audio-Visual Materials

Audio content can be created by recording sound with a smartphone or computer microphone. Audio-visual content can be created using a smartphone camera or digital camera. Video recordings are saved with file extensions such as MP4, 3GP, SVI and MOV. Audio files may have extensions such as MP3, WAV and WMA.

Video editing means removing unnecessary segments and combining useful clips into a single file. Editing can be done on computers using software such as Adobe Premiere Pro, Filmora or system video editors, and on smartphones using gallery editing tools or separate apps. The basic steps are: record, import, trim, join and export. Audio files can also be edited using tools such as audio editors and MP3 cutters from official sources.

Sketch 10: Recording, trimming, joining and exporting audio-video content.

✦ 6. Important Sketch Diagrams and Picture Notes

Diagram	What to show / conclusion
TV signal evolution	Show antenna TV, cable TV and Dish/Internet TV. Conclusion: digital and cable/satellite systems give clearer transmission than old antenna transmission.
Analogue to digital conversion	Draw sound wave -> ADC -> binary data -> DAC -> speaker. Conclusion: digital devices process data in 0 and 1.
Digital signal graph	Draw a square wave between 0 V and 5 V. Label OFF = 0 and ON = 1.
Analogue signal graph	Draw a smooth sine wave. Conclusion: analogue signal changes continuously with time.
Memory units ladder	Show bit, nibble, byte, KB, MB, GB and TB in increasing order.
Digital communication blocks	Source -> Input transducer -> Encoder -> Modulator -> Channel -> Demodulator -> Decoder -> Output transducer -> Output signal.
Baseband and broadband	Baseband: direct digital cable. Broadband: modulator, carrier wave and separate/long-distance channel.
Digital well-being balance	Show four sides: mental, physical, social and emotional well-being.
Audio-video workflow	Record -> import -> trim -> join -> export with file formats MP3/WAV/MP4/MOV.

✦ 7. Numericals and Practical Calculations

✎ Numerical solving method ·       Write: Given -> Formula / Relation -> Substitution -> Calculation -> Answer with unit. ·       For memory conversions, remember: 8 bits = 1 byte and 1024 units make the next larger unit. ·       For binary combinations, each extra bit doubles the number of possible combinations.

 

No.	Question	Solution / Answer
1	How many bits are there in 5 bytes?	1 byte = 8 bits. So, 5 bytes = 5 x 8 = 40 bits. Answer: 40 bits.
2	How many bytes are there in 3 KB?	1 KB = 1024 bytes. So, 3 KB = 3 x 1024 = 3072 bytes. Answer: 3072 bytes.
3	How many KB are there in 2 MB?	1 MB = 1024 KB. So, 2 MB = 2 x 1024 = 2048 KB. Answer: 2048 KB.
4	How many MB are there in 4 GB?	1 GB = 1024 MB. So, 4 GB = 4 x 1024 = 4096 MB. Answer: 4096 MB.
5	How many GB are there in 2 TB?	1 TB = 1024 GB. So, 2 TB = 2 x 1024 = 2048 GB. Answer: 2048 GB.
6	A file has 8192 bytes. Convert it into KB.	1024 bytes = 1 KB. 8192 / 1024 = 8 KB. Answer: 8 KB.
7	A 32 GB memory card stores data. Convert it into MB.	1 GB = 1024 MB. 32 GB = 32 x 1024 = 32768 MB. Answer: 32768 MB.
8	How many possible combinations are formed by 4 binary digits?	Each bit has 2 possibilities. 4 bits give 2^4 = 16 combinations. Answer: 16.
9	How many bits are present in 2 nibbles?	1 nibble = 4 bits. 2 nibbles = 8 bits. Answer: 8 bits or 1 byte.
10	A 10 MB audio file is saved in KB. Find its size in KB.	1 MB = 1024 KB. 10 MB = 10 x 1024 = 10240 KB. Answer: 10240 KB.
11	A video is 2048 MB. Convert it to GB.	1024 MB = 1 GB. 2048 / 1024 = 2 GB. Answer: 2 GB.
12	A digital signal sequence has 8 bits. How many bytes is it?	8 bits = 1 byte. Answer: 1 byte.

✦ 8. Comparison Tables

8.1 Analogue Signal and Digital Signal

Basis	Analogue Signal	Digital Signal
Nature	Represents a continuously changing physical quantity.	Represents a physical quantity in fixed segments or levels.
Change with time	Changes smoothly and continuously.	Changes between two fixed values such as 0 and 1.
Graph	Represented by a sine wave.	Represented by a square wave.
Example voltage	May vary continuously from -5 V to +5 V.	May have only 0 V and 5 V levels.
Converter	ADC changes analogue signal into digital signal.	DAC changes digital signal into analogue signal.
Example	Sound wave, medium wave radio, old telephone signal.	Computer data, digital TV signal, binary data.

8.2 Analogue Communication and Digital Communication

Basis	Analogue Communication	Digital Communication
Transmission style	Data are transmitted between transmitter and receiver using analogue signals.	Analogue signals are digitized, transmitted, and then converted back to analogue output.
Effect of external influence	Highly affected by noise, atmospheric effects and mixing with other waves.	Less affected by external influences.
Coding	Coding is not possible in ordinary analogue communication.	Coding is possible.
Bandwidth	Needs comparatively small bandwidth.	Needs comparatively large bandwidth.
Security and reliability	Less secure and more distortion-prone.	More secure and reliable because encoding, compression and error correction can be used.

8.3 Baseband Transmission and Broadband Transmission

Basis	Baseband	Broadband
Meaning	Digital signals are transmitted directly through a channel without converting into analogue signals.	Digital signals are converted into analogue carrier signals before transmission.
Modulation	Modulation is not required.	Modulation is required.
Distance	Used mainly for short-distance transmission.	Used mainly for long-distance and high-speed transmission.
Channel use	Sending and receiving happen in the same channel.	Separate channels or separate cables may be used for sending and receiving.
Example	Two computers connected with a cable.	Broadband internet, optical/electromagnetic wave transmission.

8.4 Positive and Negative Effects of Digital Technology

Area	Positive Effect	Negative Effect
Education	Digital library, audio-visual learning and internet search help study.	Overuse can reduce concentration and physical book-reading habit if not balanced.
Communication	Social networks connect people over long distance.	Cybercrime, reputation damage and stress can occur.
Finance and business	Digital payment and online business save time and expand services.	Fraud and misuse can harm users if security is weak.
Health and lifestyle	Digital health tools and information are useful.	Excessive screen time can cause obesity, eye strain, insomnia and stress.
Entertainment	Games, music and videos provide recreation.	Violent/addictive games can affect mental health and social behavior.

8.5 Digital Integrity and Digital Reputation

Basis	Digital Integrity	Digital Reputation
Meaning	Truthfulness, reliability and consistency of digital information and behavior.	Public image or credibility created by online activities.
Focus	Whether data/profile/behavior is genuine and trustworthy.	How others judge a person or organization online.
Examples	Using correct information, avoiding fake posts, respecting intellectual property.	Profile photo, real name, comments, shares, followers and organizational pages.
Management	Verify information, cite sources, protect data and use secure accounts.	Use authentic profile details, consistent username, privacy settings and timely response to comments.

8.6 File Formats

Type	Formats	Use
Audio file formats	MP3, WAV, WMA	Used for sound recordings and audio editing.
Video file formats	MP4, 3GP, SVI, MOV	Used for camera recordings, video clips and audio-visual materials.

✦ 9. Activity and Project Summaries

Activity / Project	Notebook Summary
Activity 13.1 - Digital signal graph	Make a circuit with 5 V source, bulb, switch and wire. Record ON as 1 and OFF as 0. Draw a square wave graph of high and low signals.
Activity 13.2 - Broadband speed test	Open an internet browser and use speedtest.net to measure the speed of the internet service being used.
Activity 13.3 - Digital device use at home	Find average screen time of household members and discuss long-term effects of continuous digital device use.
Activity 13.4 - Digital wellbeing app	Install or observe a digital wellbeing app. Note daily phone use, app timers, notification control and other features.
Activity 13.5 - Video recording	Use a smartphone, spring balance and 500 g object. Record slow-motion video to observe pointer motion during falling.
Activity 13.6 - Video editing	Copy the video to a computer, trim unnecessary parts, join clips if needed, finish/export and save the final video file.
Project work	Prepare and conduct a debate on: use of digital technology has a positive impact on society.

✦ 10. Exercise Answer Key and Model Answers

10.1 Choose the correct option

No.	Question clue	Correct answer
1(a)	Which represents an analogue signal?	(iv) Medium wave radio.
1(b)	Which indicates 1 byte memory?	(ii) 00000000, because 1 byte = 8 bits.
1(c)	Correct order in digital signal transmission	(iii) Source -> input transducer -> encoder -> modulator -> channel -> demodulator -> decoder -> output transducer.
1(d)	Audio file format	(iii) MP3.
1(e)	Posting information about new scientific discoveries from time to time on social networks indicates	(iv) Digital reputation management.

10.2 Differentiate

(a) Analogue Signals and Digital Signals: use Table 8.1.

(b) Analogue Signal Transmission and Digital Signal Transmission: use Table 8.2.

(c) Digital Integrity and Digital Reputation: use Table 8.5.

10.3 Short and Long Answer Model Answers

Question	Model Answer
Define bit and byte used in computer memory.	A bit is the smallest form of data in a computer and can be either 0 or 1. A byte is a group of 8 bits or 2 nibbles that works as a single unit of data.
Present currently used high-speed internet as broadband transmission.	Broadband internet is a high-speed transmission system in which digital data are converted into analogue carrier signals by modulation and transmitted over suitable channels such as cable, optical or electromagnetic media. It is suitable for long-distance and high-speed data communication.
Write four advantages of digital transmission.	Noise effect is low; circuits are reliable; information can be encoded/compressed for security; error detection and correction reduce mistakes. Other points: less cross-talk, stable signal properties and cheaper circuit design.
Explain impact of digital technology on ICT with two examples.	Digital telecommunication makes fast communication possible and allows many telephone calls through one channel. Digital media and digital TV allow online information sharing, HD television and satellite/cable/internet services.
Give four examples of digital technology used daily.	Digital wallet, online newspaper, digital library, smartwatch. Other examples: digital camera, calculator, speedometer, infrared/digital thermometer, calendar.
Write two positive and two negative effects of digital technology.	Positive: digital library helps learning; digital payment makes transactions easier. Negative: excess screen time may cause health problems; cybercrime or reputation damage may cause stress.
Define digital citizenship.	Digital citizenship is the responsible citizenship of netizens in the virtual world of the internet, including respectful, safe and ethical online behavior.
Write four characteristics of a good netizen.	Uses polite language, respects others, protects privacy, credits sources/intellectual property. Also avoids cybercrime, shares reliable information and manages screen time.
What is online reputation? Write with examples.	Online reputation is the public image and credibility created by online profile, posts, comments, shares and privacy. Example: a person using real name and useful scientific posts builds a positive reputation; an organization replying to complaints on its website manages institutional reputation.
What is digital well-being?	Digital well-being is the state of being healthy mentally, physically, socially and emotionally by balancing online and offline activities.
Write advantages of digital well-being.	It reduces screen addiction, protects mental and physical health, improves focus, supports social life and helps manage time through app limits and notification control.
What four precautions are necessary for digital well-being?	Set screen-time limits, take regular breaks and exercise, turn off unnecessary notifications during work/study, avoid harmful/addictive online content and use digital wellbeing apps if needed.
What is digital reputation management?	It is the careful management of online profile, privacy, posts, comments and institutional pages to maintain credibility and positive public impression.
Give two examples of digital reputation management.	Using a real profile with consistent username; responding politely and quickly to comments or complaints on an organization's website/social media.
Mention four importance of digital reputation management.	Builds trust, protects personal/organizational image, reduces harm from misuse or cybercrime, supports credibility for study, work, business and public communication.
Write two positive effects of social media.	Connects people across distance; gives a public platform to express opinions and share useful information.
Write two negative effects of social media.	May spread cybercrime or reputation damage; excessive use may cause stress, isolation and changed social behavior.
Plan a 5-minute audio-visual material and reduce it to 3 minutes.	Plan: choose topic, write script, collect images/props, record audio/video, import to editor, arrange clips, add title and export. To make it 3 minutes: trim repeated or unnecessary parts, keep only key explanations, shorten transitions, join useful clips and export final video.

✦ 11. Questions for Brainstorming

1.  Why does a digital signal use only two values, 0 and 1, even when real-world signals change continuously?

2.  Why is old antenna TV usually less clear than cable TV or Dish TV?

3.  How does ADC help a computer understand sound from a microphone?

4.  How does DAC help a speaker play music stored in digital form?

5.  Why does each extra binary digit double the possible combinations?

6.  Why is digital communication less affected by external noise than analogue communication?

7.  Why does broadband transmission need modulation?

8.  Why is baseband transmission mostly useful for short distances?

9.  How can digital technology improve education in Nepal?

10.  What can happen if a person uses social media without privacy settings?

11.  Why should online posts be considered permanent?

12.  How can an organization improve online reputation through social media?

13.  Why is citing sources important for a good netizen?

14.  How can excessive online gaming affect physical and mental health?

15.  What daily routine can balance screen time and offline activity?

16.  What precautions should students take while searching learning materials on YouTube or websites?

17.  How can a 5-minute video lesson be edited into a clear 3-minute video?

18.  What are the advantages and disadvantages of digital payment in local markets?

19.  How can digital libraries develop reading habits?

20.  What is the difference between being active online and being responsible online?

✦ 12. Quick Revision and Exam Tips

·       Signal is a physical quantity that changes with time.

·       Analogue signal changes continuously and is shown by a sine wave.

·       Digital signal changes between fixed values and is shown by square waves or binary digits.

·       ADC converts analogue signal into digital; DAC converts digital signal into analogue.

·       Bit is 0 or 1; 4 bits = 1 nibble; 8 bits = 1 byte.

·       1024 bytes = 1 KB; 1024 KB = 1 MB; 1024 MB = 1 GB; 1024 GB = 1 TB.

·       Digital communication order: Source -> Input transducer -> Encoder -> Modulator -> Channel -> Demodulator -> Decoder -> Output transducer -> Output signal.

·       Digital transmission has low noise, good reliability, coding, compression and error correction.

·       Baseband sends digital signals directly; broadband converts digital signals into analogue carrier signals for transmission.

·       Digital citizenship means responsible behavior as a netizen.

·       A good netizen is polite, respectful, secure and honest, and cites sources.

·       Online reputation depends on profile, posts, comments, shares and privacy settings.

·       Digital well-being balances mental, physical, social and emotional health.

·       Video editing includes trimming unwanted parts, joining clips and exporting final files.

✎ Final exam tip ·       For comparison questions, draw a table with Basis, first term and second term. ·       For digital communication, memorize the full block order. ·       For numericals, show unit conversions clearly. ·       For long questions on digital well-being and online reputation, include examples from daily life.