Information and Communication Technology: Grade 10 Science

You send a voice message to a friend in Pokhara. In a fraction of a second your voice becomes electricity, the electricity becomes a long string of 0s and 1s, the 0s and 1s ride on radio waves to a tower, through glass fibers under the road, perhaps up to a satellite and back, and at the other end they are turned back into your voice. Not one word is lost on the way.

This unit is about how that is done: the difference between analog and digital signals, how a digital message is coded, sent and received, and why nearly everything, from TV to money, has gone digital. It is also about you online: being a good digital citizen, guarding your reputation, keeping your balance between the screen and the rest of life, and making videos of your own.

Television: antenna, cable and dish

There are three ways a TV program can reach a home.

Antenna TV. A TV station sends the program from a tall transmitter as radio waves. An antenna on the roof catches them. As the waves travel through the air, they spread out and lose energy, so they make only a small voltage (potential difference) in the antenna, and only a weak current in the wire to the TV. This weak current is the modulated signal that carries the picture and sound. Hills, buildings and weather weaken it further. That is why antenna TV had the poorest picture and sound of the three.
Cable TV. A cable company collects many channels and sends them along cables strung on poles to each house. The signal in the cable is also modulated. Before Dish TV, cable was the most popular way to watch TV in Nepal. To use a computer as a TV, or to get internet through the same cable, you need a cable modem.
Dish TV (satellite TV) and internet TV. A dish on the roof receives digital signals sent down from a satellite far above the Earth. Internet TV (IPTV) comes as digital data through the internet connection.

Figure 13.1 Three ways a TV program reaches a home: through the air to an antenna, along a cable from a cable company, or down from a satellite to a dish.

TV antennas on poles above red tiled roofs: each is a long metal rod with many short crossbars, pointing the same way — **Figure 13.2** TV antennas on the roofs of Aigues-Mortes, a town in France. The short metal rods catch the radio waves from the transmitter, and each antenna is turned to face it. Photo: Luk, CC BY-SA 3.0

Inside a modern TV, the incoming signal is turned into digital signals by the TV’s own circuits. But your eyes and ears can’t use 0s and 1s: in the end, the digital signal must be turned back into the analog signals that make light on the screen and sound in the speaker.

Figure 13.3 A geostationary satellite circles the Earth above the equator, 35,786 km up, once every 23 hours 56 minutes: exactly as fast as the Earth turns. Seen from the ground it seems to stand still, so a dish can be pointed at it once and left. From Nepal, north of the equator, the dish points south and up.

A satellite dish and solar panels inside a stone wall in a high Himalayan village, with snowy mountains behind — **Figure 13.4** A satellite dish at Pheriche (about 4,370 m) in the Khumbu, powered by solar panels. Satellites bring TV and internet even where no cable can reach. Photo: Vyacheslav Argenberg, CC BY 4.0

Analog and digital signals

From sound to numbers and back

When you speak, your voice is a wave of air pressure that rises and falls smoothly. A microphone turns it into a voltage that also rises and falls smoothly, copying the sound. A signal like this, which changes continuously, is analog (it is an analog, a copy, of the sound).

To send it digitally, a device called an analog-to-digital converter (ADC) measures the voltage many times a second and writes each measurement as a number in binary, using only 0s and 1s. At the other end, a digital-to-analog converter (DAC) turns the numbers back into a smoothly changing voltage, and a loudspeaker turns that back into sound.

Figure 13.5 Sound becomes a voltage (analog), the ADC turns it into binary numbers (digital), and the DAC turns them back into a voltage for the loudspeaker (analog).

Digital signals are so easy to send that they now carry almost all information and communication. People who have grown up with phones, the internet and social media are sometimes called digital natives. How we behave online now matters as much as how we behave anywhere else. Courtesy and kindness in online conversation build a good online reputation; careless or unkind use of online tools can harm our own and other people’s physical, mental and emotional health. We come back to this at the end of the unit.

Digital signal: Activity 13.1

Activity

13.1: a signal made by a switch

Make a circuit with a 5 V supply, a switch, a bulb and connecting wires. When the switch is on, the potential difference across the bulb is 5 V: call this a high signal, 1. When the switch is off, it is 0 V: a low signal, 0. Switch it on and off in some pattern, say once a second, and record the voltage at each second in a table. Then draw a graph of voltage against time.

Time (s)	1	2	3	4	5
Potential difference (V)	0	5	5	0	…
Signal	0	1	1	0	…

What you should see

The graph is made of flat steps that jump straight between two levels, 0 V and 5 V, with nothing in between. It looks like a row of boxes: a square wave. That is a digital signal. (Use a d.c. supply, such as a 5 V phone charger or four 1.2 V cells: it gives clean steps, while with a.c. the “on” parts of the graph would wobble.)

Any physical quantity that changes with time and carries information is a signal. In Activity 13.1, you made a digital signal by flicking a switch. Inside electronic devices, millions of tiny switches called transistors do the same, billions of times a second.

If you never switch off, and measure the voltage of the a.c. mains across the bulb, the graph rises and falls smoothly through every value between −V and +V: an analog signal.

Figure 13.6 A digital signal (left) has only two values, here 0 V and 5 V, and jumps between them. An analog signal (right) changes smoothly through every value, here between −5 V and +5 V.

Binary numbers

A digital signal uses only two digits, 0 and 1, so it counts in the binary system. Each 0 or 1 is called a bit (short for binary digit). With more bits, you can make more patterns:

Number of bits	Possible patterns	How many
1	0, 1	2
2	00, 01, 10, 11	4
3	000, 001, 010, 011, 100, 101, 110, 111	8
4	0000 … 1111	16
8	00000000 … 11111111	256

Each extra bit doubles the number of patterns: n bits give $2^n$ patterns. Every pattern can stand for a number, a letter, a color or a note of music. You can picture each bit as a switch, on for 1 and off for 0; for example 0011 means the last two switches are on.

Storing data: bits and bytes

These patterns of bits are stored in a computer’s memory: text, pictures, sound and video, all as 0s and 1s. Memory is measured in these units:

Unit	Equal to
1 bit (binary digit)	a single 0 or 1
1 nibble	4 bits
1 byte	8 bits (2 nibbles)
1 kilobyte (KB)	1024 bytes
1 megabyte (MB)	1024 KB
1 gigabyte (GB)	1024 MB
1 terabyte (TB)	1024 GB

A bit is the smallest piece of data in a computer: a single 0 or 1.
A byte is a group of 8 bits that the computer handles as one unit. One byte can store one letter of English text.

A story from science

The man who measured information

In 1948, an American engineer, Claude Shannon, published a paper that showed how to measure information itself. He showed that any message, a word, a picture, a song, can be written as a string of yes-or-no answers, and he called each answer a bit (a word his colleague John Tukey had suggested). He also worked out the fastest rate at which information can be sent through a noisy channel, and proved that, with cleverly chosen extra bits added to a message, it can get through almost without mistakes. (The first practical error-correcting codes were invented soon after by his colleague Richard Hamming.) Every phone, Wi-Fi router and satellite link today is built on his ideas. Shannon also loved toys: he built a juggling machine, a mechanical mouse that could learn a maze, and rode a unicycle through the corridors of his lab.

A black-and-white portrait of a man in a jacket and tie — **Figure 13.7** Claude Shannon (1916–2001), who founded information theory and made the bit the unit of information. Photo: Tekniska museet, Stockholm, CC BY 2.0

Analog and digital signals compared

Analog signal	Digital signal
A signal that represents a physical quantity that changes continuously.	A signal that represents a physical quantity in separate steps.
It can take any value in a range at any moment.	It has only two values, which it switches between (0 and 1).
Drawn as a smooth wave, such as a sine wave, e.g. from −5 V to +5 V.	Drawn as a square wave, e.g. between 0 V and 5 V.
An ADC turns it into a digital signal (e.g. in a digital thermometer, the temperature sensor’s signal).	A DAC turns it into an analog signal (e.g. playing music on a computer).

This is what an ADC does. It measures the wave at regular moments (samples) and rounds each measurement to the nearest level it can write with its bits. Change the number of samples and bits: how many does it take before the steps look like the smooth wave?

Samples: 12 Bits per sample: 2

Levels: 2² = 4
Bits to store: 12 × 2 = 24
Average error: 40%

First samples in binary: 10 10 10 11

The staircase is a poor copy: you would hear this as harsh, crackly sound. Add samples or bits.

Which of these gives an analog signal?

Pick an answer to see why.

Signal transmission

We talk using sound, an analog signal. An old landline telephone turns your voice into an analog electrical signal and sends it along a wire. Sending a signal from one place to another through a medium, or channel (a wire, a glass fiber, the air), is called signal transmission. Signals can be sent as voltages in wires, as light in fibers, or as electromagnetic (radio) waves through the air.

Older ways of communicating used analog signals. Radio stations on medium wave (MW) and short wave (SW) send analog signals. On the way, other waves, lightning and the atmosphere add noise: the hiss and crackle you hear on an MW radio at night. Analog telephone calls could also be secretly recorded by anyone who tapped the wire.

The answer to both problems is to digitize the signal: turn it into 0s and 1s. A receiver only has to decide “is this a 0 or a 1?”, so a little noise does no harm, and the data can be locked with a code. In a digital system, data can be stored, transmitted and recreated using only 0s and 1s; processing it is easier, and errors are much rarer.

Components of a digital communication system

Figure 13.8 A digital communication system. The sender’s side (top) turns a sound into coded 0s and 1s carried on a wave; the receiver’s side (bottom) undoes each step in reverse order.

Source: the original message, for example the sound of your voice.
Input transducer: turns the message into an electrical signal. A microphone turns sound into electricity. (A transducer is anything that changes one form of energy into another.)
Encoder: turns the signal into bits and compresses the data into as few bits as possible, so it takes up less of the available range of frequencies, the bandwidth. It can also add check bits and lock the data with a code.
Modulator: puts the bits onto a carrier wave (a radio wave or light) so they can travel through the channel. The digital sequence becomes an analog wave.
Channel: the path from the transmitter to the receiver: a wire, an optical fiber, or the air (radio waves). Noise gets in here.
Demodulator: the first step at the receiver. It takes the bits back off the carrier wave.
Decoder: turns the received bits back into the message, using the check bits to find and correct errors.
Output transducer: turns the electrical signal back into the original physical form. A loudspeaker turns current into sound.
Output signal: the result. If sound went in, sound comes out.

The order matters, and exams ask it: source → input transducer → encoder → modulator → channel → demodulator → decoder → output transducer → output. Notice the receiver does the sender’s steps in reverse.

Type a short word and follow it through every step. Then turn up the noise in the channel: at what point do mistakes start? Press Send again to try with new random noise.

1 Source: your message

2–3 Input transducer and encoder: 8 bits a letter 01001110 01000001 01001101 01000001 01010011 01010100 01000101

4–5 Modulator: a 0 is one wave, a 1 is two. Channel: noise is added.

Noise in the channel: 60%

6 Demodulator: the bits it reads (0 wrong) 01001110 01000001 01001101 01000001 01010011 01010100 01000101

7–9 Decoder and output: the message received NAMASTE

Every bit arrived correctly: the receiver only has to tell “one wave” from “two waves”, and a little noise can’t fool it.

Analog and digital communication compared

Analog communication	Digital communication
Data is sent from transmitter to receiver as analog signals.	Analog signals are digitized, sent, and turned back into analog signals at the end.
Noise and other outside influences affect it a lot.	Outside influences affect it much less.
Coding is not possible.	Coding (for privacy and error checking) is possible.
Needs a small bandwidth.	Needs a large bandwidth (unless the data is compressed).

Baseband and broadband transmission

Figure 13.9 Baseband (top): the 0s and 1s go down the cable as they are, one signal at a time. Broadband (bottom): each signal is modulated onto its own carrier frequency, so many signals share one cable or fiber at once.

Baseband transmission sends digital signals through the channel as they are, without turning them into analog waves. The whole channel carries one signal at a time, used for both sending and receiving. It is used over short distances: connecting one computer to another with a cable, as in a school computer lab, is baseband.

Broadband transmission first modulates the digital signals onto carrier waves (analog), as electromagnetic waves or as light in optical fibers. Different signals use different carrier frequencies, so many can travel through the same channel at once; the channel is divided into separate channels for sending and receiving (or two separate cables are used). It is used over long distances. In everyday language, “broadband internet” simply means fast internet, and it is broadband in this sense too.

Figure 13.10 Three ways a modulator can put the bits 0 1 1 0 1 onto a carrier wave: change its height (amplitude-shift keying, ASK), its frequency (frequency-shift keying, FSK), or its timing, the phase (phase-shift keying, PSK).

Activity

13.2: how fast is your internet?

On a phone or computer connected to the internet, open a speed-test website such as speedtest.net and press GO. Note the download and upload speeds (in megabits per second, Mbps) and the ping (how many milliseconds a signal takes to get there and back). Compare with friends who use other internet providers or mobile data.

Internet provider	Download speed	Upload speed
e.g. Nepal Telecom (4G wireless home)

What the numbers mean

Speeds are in megabits per second, not megabytes. 80 Mbps is 80 ÷ 8 = 10 MB every second, so a 500 MB video downloads in about 50 s. Speeds change with the time of day: in the evening, when everyone is online, they usually drop.

In which kind of transmission are many signals sent through one cable at the same time, each on its own frequency?

Pick an answer to see why.

Advantages of digital transmission

Noise and distortion affect digital signals very little.
Digital circuits are much more reliable.
Digital circuits are cheaper and easier to design than analog ones.
There is less overlap and cross-talk between signals.
The properties of digital signals don’t change under normal conditions.
Information can be kept secure by encoding (encryption), and made smaller by compression.
Error-detecting and error-correcting codes mean fewer mistakes in transmission.

How digital technology changed communication

Digital technology has made information and communication faster, better and available to far more people. Modern telecommunication, the internet, digital media and digital TV all grew out of it.

a.Digital telecommunication. Calls connect fast and sound clear. Many telephone calls can be sent at once through a single channel or bandwidth, each as its own stream of bits.
b.Digital media. Phones, computers and tablets let us create our own media, watch the news, and share information online.
c.Digital TV. Digital TV comes by different routes, each with its own strengths: terrestrial (from a transmitter tower to an antenna), satellite (to a dish; Dish TV has spread TV service to remote parts of Nepal), cable (from a cable company’s center, the headend, along cables), and mobile (to phones and cars). High-definition (HD) TVs are built with the latest digital technology.

How a message crosses the internet

When you send a photo, the internet doesn’t open one long wire to your friend. It cuts the photo into small packets of bits, writes the destination address and a number on each, and sends them off. Machines called routers pass each packet towards the address, each choosing a good next step at that moment. Different packets may take different roads and arrive out of order; your friend’s phone puts them back in order by their numbers, and asks again for any that went missing.

Send the message and watch its packets find their way. Then cut a cable (tap one) and send it again: the network simply routes around the break. This is why the internet was designed this way: no single broken link can stop it.

Arrived, first to last

····

Put in order by number

················

= HELLO FROM NEPAL

Press Send. The message is cut into four numbered packets, and each finds its own way.

Digital technologies in daily life

Digital devices make daily work easier in education, health, entertainment and money:

infrared and digital thermometers (temperature shown as numbers)
calculators
online newspapers
digital wallets, such as the apps used to pay by QR code
online libraries (e-libraries)
digital speedometers in vehicles
digital cameras and phone cameras
smartwatches
digital calendars

Positive effects

Digital libraries: digital copies of textbooks and other books, like those in the CDC’s online library, build reading habits and reach students anywhere.
Online newspapers: with the internet and a smartphone, you can read news portals such as gorkhapatraonline.com.
Digital payment: no need to carry a lot of cash. Scan a shop’s QR code and money goes straight to its bank account. You can also pay taxes, and book bus and plane tickets.
Online business: goods can be advertised and sold over the internet.
Social networks: people can share their opinions publicly, and stay connected with family and friends far away.
Entertainment: games and music apps.

Negative effects

People who spend too long online may change how they behave with others face to face.
Crimes can be committed through social media, harming people’s personal, family and social lives; a damaged reputation causes great mental stress.
Reading and buying more digital material means less use of physical things like printed books, and some businesses lose work.
Children who don’t exercise enough risk obesity and weakness.
Games full of killing and violence can harm mental health and social behavior.
Misuse of digital technology harms others, for example through cybercrime (fraud, hacking, cyberbullying).

The internet is behind most of these effects, good and bad. People all over the world spend a long time online doing similar things, and an active internet user is called a netizen (a citizen of the net).

Digital citizenship

In the age of the internet, everyone has the same right to use it and take part in it. A netizen is a person who actively uses the internet: a citizen of the worldwide, connected internet. Digital citizenship is being a responsible citizen of that online world. Telephones, internet calls and social networks connect people across the world so closely that the world is often called a global village.

Qualities of a good netizen

Behave online in a way that is socially acceptable, as you would face to face.
Use polite, decent language in emails, chats, comments and public posts.
Respect others, even people you will never meet. There is a real person on the other side of every screen.
Remember that anything posted online is permanent. It can be copied, shared and found years later, even after you delete it.
Respect intellectual property: photos, music, writing and videos online belong to the people who made them. Don’t use them without permission, and always cite the source.
Don’t spread rumors or unchecked news; check before you share.
Protect your own and others’ privacy and security.

Online reputation

Just as in daily life, your reputation online, what people think of you from what they see of you on the internet, needs looking after.

A genuine profile, with your real name, a real photo and true public details, shows that the profile is authentic and can be trusted. (For students, keep the public details few: your name is enough. Never put your phone number, home address or school timetable in public.)
Using the same user name on all your social media profiles makes you easy to recognize.
Your posts, comments and shares show your knowledge, interests and skills, or your carelessness.
Security matters: poor privacy settings can lead to stolen passwords and someone else posting harmful things in your name.

Reputation online belongs to organizations too. Information on an organization’s website and posts on its social media pages are official. The number of followers of its page shows how far it is trusted. A good organization is present on the major sites and networks, and manages its reputation by answering comments and complaints promptly.

It opens with a password that looks clever: how long would a computer making 100 million guesses a second take to find it? Then type made-up passwords of your own (not your real one; nothing you type leaves this page).

A made-up password

Strength: Very weak
Time to guess it: less than a second
Length: 12 characters

Found almost at once. Common passwords, names, places and years are the first things guessing programs try.

A rough guide only: real attackers use huge lists of leaked passwords and clever rules. Nothing you type here is saved or sent anywhere.

Which of these is the strongest password?

Pick an answer to see why.

Digital wellbeing

Sitting online for hours without balancing it with other activities harms health. It can cause obesity, sleeplessness (insomnia), eye problems and stress, and uncontrolled internet use can lead to depression, anxiety, dishonesty, low self-esteem, isolation, loneliness and aggression.

Digital wellbeing is being healthy mentally, physically, socially and emotionally by balancing the time spent on online and offline activities. When we use online technology, we should look after our digital health so that it doesn’t harm our overall health.

Figure 13.11 Digital wellbeing is a balance of four kinds of health. Too much screen time pulls each one down; time offline lifts it back.

Cautions for digital wellbeing

Addiction to digital technology makes life chaotic. Digital wellbeing skills mean knowing the effects of needless screen use and building habits to control it:

set aside fixed screen-free times (meals, homework, the hour before sleep);
set time limits for social media and games;
turn off notifications while working or studying;
keep the phone out of the bedroom at night;
take a break every 20 minutes: look at something 20 feet (6 m) away for 20 seconds, to rest your eyes.

Apps can help. Android phones have Digital Wellbeing built into their settings, and iPhones have Screen Time; apps such as ActionDash, Digital Detox and Microsoft Launcher do the same. They show how long you spend in each app and let you set limits.

The internet is full of learning materials, from lessons and experiments to whole courses. In Nepal, the National Centre for Educational Development (NCED) publishes video lessons. While searching and watching, keep your digital wellbeing in mind: decide in advance what you are looking for and how long you will spend, so a 5-minute search doesn’t become a 2-hour scroll.

Making audio and audio-visual materials

You can make your own learning materials. Audio content is made by recording sound with the microphone of a computer or phone. Audio-visual content (video) is recorded with a phone camera or a digital camera.

Activity

13.5: a falling spring balance, in slow motion

You need: a smartphone that can record slow-motion video, a spring balance, and a 500 g mass to hang on it.
Hang the mass on the spring balance and hold the top of the balance up high. A friend starts filming in slow motion. Let go of the balance (with something soft below to catch it). Watch the video: what does the pointer do while the balance is falling?

What you should see

While the balance and the mass are falling freely, the pointer springs back to zero: the balance reads no weight at all. Falling together, the mass doesn’t pull on the spring. This is weightlessness, exactly what astronauts feel in orbit, where they are falling freely around the Earth (you met this in Unit 7). Slow-motion video lets you see something that happens too fast for your eyes.

The recorded file’s name ends with an extension that tells its format: a video saved as class 10 ICT.mp4 is an MP4 file. Other video formats are 3GP, AVI, MOV and MKV. Audio formats include MP3, WAV, WMA and AAC.

Video editing

If some part of a recording isn’t needed, it can be cut out, and two or more clips can be joined into one file. This is video editing. It needs an app on a phone or software on a computer, such as Adobe Premiere Pro or Filmora, or the editor that comes with Windows (the Photos app’s Video Editor on older versions; Clipchamp on Windows 11).

Figure 13.12 Trimming a clip: drag the start and end markers to keep only the part you want. Joining clips: put them one after another on the timeline, then save (export) them as one file.

Activity

13.6: cut and join a video

Copy the video from Activity 13.5 to a computer.

a. Cutting (trimming)

Open the video editor (search for it from the Start menu), start a New video project and give it a name, such as Class 10 ICT.
Add your video to the project library and drag it onto the editing panel (the timeline or storyboard).
Select the clip and choose Trim. Play it, and drag the two markers to the start and the end of the part you want to keep. Check the clip’s length and press Done.
Choose Finish video (or Export), pick the quality, and save the file, for example on the desktop.

b. Joining

Copy the clips made by everyone in your group into one folder.
Start a new project, add all the clips to the library, and drag them onto the timeline in order.
Choose Finish video or Export, and save the joined video.

On a phone: open the video in the gallery, tap the edit (pencil) icon, and use Trim/Cut and Crop. If your phone has no editor, install one from the Play Store or App Store.

Audio editing works the same way. If no audio editor is installed, a free one such as Audacity (from audacityteam.org) can be downloaded and installed; always download software from its official website or the official app store, never from unknown links.

Project work

Exercise

1. Choose the correct option

a. Which of the following uses an analog signal?

Pick an answer to see why.

b. Which of these is 1 byte of memory?

Pick an answer to see why.

c. Which is the correct order of the steps of digital signal transmission?

Pick an answer to see why.

d. Which of the following is an audio file format?

Pick an answer to see why.

e. Someone regularly posts news of new scientific discoveries on social networks. What does this show?

Pick an answer to see why.

2. Differentiate between

Analog signals and digital signals

Answer

Analog signal	Digital signal
Changes continuously with time.	Changes in steps, between fixed values.
Can have any value in a range.	Has only two values (0 and 1).
Shown by a sine wave.	Shown by a square wave.
Easily affected by noise.	Little affected by noise.
e.g. the voltage from a microphone, MW radio	e.g. data in a computer, a switch turned on and off

Analog signal transmission and digital signal transmission

Answer

Analog transmission	Digital transmission
The signal is sent as an analog signal all the way.	The signal is digitized, sent as bits, and turned back to analog at the end.
Strongly affected by noise and outside influences.	Much less affected.
No coding possible, so less secure.	Coding possible: secure, with error correction.
Needs a small bandwidth.	Needs a larger bandwidth (unless compressed).
e.g. MW and SW radio, old landline phones	e.g. mobile phones, the internet, Dish TV

Digital integrity and digital reputation

Answer

Digital integrity	Digital reputation
Being honest and responsible online: what you do.	What others think of you from what they see of you online.
Comes from inside: telling the truth, citing sources, not copying others’ work, not cheating, not using fake accounts, keeping promises.	Is built up over time from your posts, comments, shares, profile and what others say about you.
You keep it even when no one is watching.	Depends on what is visible to others.
e.g. writing a project in your own words and listing your sources	e.g. a profile known for helpful, accurate science posts

Good integrity, over time, is the surest way to a good reputation.

3. Answer the following questions

Define the bit and the byte used in computer memory.

Answer

A bit (binary digit) is the smallest unit of data in a computer: a single 0 or 1. A byte is a group of 8 bits that the computer handles as one unit; one byte can store one letter of text.

Explain how today’s high-speed internet is a broadband transmission.

Answer

In broadband transmission, the digital data is modulated onto carrier waves, as light in optical fibers or as radio waves for 4G and Wi-Fi. Different streams of data use different carrier frequencies, so many signals, for sending and receiving, travel through the same fiber or air at the same time and over long distances. Because so many channels share the medium at once, a very large amount of data flows every second, which is why it is fast. (Speeds are measured in megabits per second with a speed test.)

Write four advantages of digital transmission.

Answer

Any four:

1.noise and distortion affect it very little;
2.the circuits are more reliable;
3.digital circuits are cheaper and easier to design;
4.less overlap and cross-talk between signals;
5.data can be kept secure by encryption, and compressed;
6.error-detecting and error-correcting codes reduce mistakes;
7.copies are perfect.

Explain the impact of digital technology on the development of information and communication technology, with any two examples.

Answer

Digital technology has made communication faster, clearer, cheaper and available to far more people.

Digital telecommunication: calls connect quickly and sound clear, and many calls share one channel at once, so mobile phones reach almost everyone, even in remote villages.
Digital TV: compression fits many channels into the space of one, and satellite (Dish TV) brings clear pictures to remote parts of Nepal.

(Also: the internet, digital media, online payment, e-libraries.)

Give four examples of digital technology used in daily life.

Answer

Any four: digital (and infrared) thermometer, calculator, digital wallet / QR payment, online newspaper, online library, digital camera, smartwatch, digital speedometer, digital calendar, mobile phone.

Write two positive and two negative effects of digital technology in daily life.

Answer

Positive:

1.digital payment: no need to carry cash, and taxes and tickets can be paid from home;
2.digital libraries and online learning make books and lessons available anywhere.

Negative:

1.too much screen time leads to lack of exercise, obesity, eye strain and poor sleep;
2.cybercrime, such as online fraud and cyberbullying, harms people and their reputation.

Define digital citizenship.

Answer

Digital citizenship is being a responsible citizen (netizen) of the online world: using the internet and digital technology safely, respectfully, honestly and lawfully, with an awareness of one’s rights and duties online.

Write four qualities of a good netizen.

Answer

Any four:

1.uses polite, decent language online;
2.respects others, even people never met;
3.remembers that posts are permanent and thinks before posting;
4.respects intellectual property and cites sources;
5.checks facts before sharing;
6.protects their own and others’ privacy and security.

What is online reputation? Give examples.

Answer

Online reputation is the impression people form of a person or organization from what they can see of them on the internet: their profile, posts, comments, shares, and what others say about them.
Examples: a student known for sharing accurate science news has a good online reputation; a person whose old rude comments are found by a future employer has a damaged one; a business that answers customers’ complaints quickly on its page earns a good reputation, and the number of its followers shows people’s trust.

What is digital wellbeing?

Answer

Digital wellbeing is the state of being healthy mentally, physically, socially and emotionally by balancing the time spent on online and offline activities, so that the use of technology doesn’t harm overall health.

Write the advantages of digital wellbeing.

Answer

Good digital wellbeing:

1.protects physical health: more exercise and sleep, less eye strain and obesity;
2.protects mental and emotional health: less stress, anxiety and addiction;
3.improves concentration and study, with fewer distractions;
4.keeps real-life relationships with family and friends strong;
5.makes us use technology on purpose, as a tool, instead of being used by it.

What four precautions are necessary for digital wellbeing?

Answer

1.Set fixed screen-free times, such as at meals and before sleep.
2.Set time limits for social media and games (an app timer helps).
3.Turn off notifications while studying or working.
4.Take regular breaks, exercise and spend time with people offline.

(Also: keep the phone out of the bedroom at night; use a digital wellbeing app.)

What is digital reputation management?

Answer

Digital reputation management is the work of building, protecting and improving one’s reputation (or an organization’s) on the internet: posting responsibly, keeping profiles genuine and secure, removing or correcting harmful content, and, for organizations, answering comments and complaints promptly.

Give two examples of digital reputation management.

Answer

1.A student keeps the same real name on all profiles, sets strong privacy settings, and regularly shares useful, accurate posts on science.
2.A hospital answers patients’ complaints on its social media page quickly and politely, and keeps its official website up to date.

Mention four reasons digital reputation management is important.

Answer

Any four:

1.Employers, colleges and scholarship committees often look people up online.
2.Posts are permanent, and a careless one can harm a person for years.
3.Good security and privacy settings prevent stolen passwords and fake posts in one’s name.
4.For an organization, a good reputation brings trust, customers and followers.
5.It protects mental health: online attacks on a reputation cause great stress.

Write two positive effects of using social media.

Answer

1.It keeps people connected with family and friends far away, including those working abroad.
2.It spreads useful information quickly: news, learning materials, warnings during floods and earthquakes, and lets people share their opinions publicly.

(Also: online business and promotion.)

Write two possible negative effects of using social media.

Answer

1.Addiction and too much screen time, leading to poor sleep, less study and less time with people face to face.
2.Cyberbullying, fake news and rumors, and fraud, which harm people’s reputations and mental health.

Write your plan for a 5-minute audio-visual lesson on any one unit of Grade 10 science. How could it be made 3 minutes long? Write the steps.

A sample plan

Topic: Unit 11, the transformer.
5-minute plan:

Opening (30 s): show a phone charger and ask, “How does 230 V become 5 V?”
Construction (1 min): film a real transformer (from an old adaptor) or a drawing, and name the core and the two coils.
Working (1.5 min): explain mutual induction, with a coil and a compass or LED.
The formula and an example (1.5 min): write $N_p/N_s = V_p/V_s$ and solve the router-adaptor example.
Summary and a question for viewers (30 s).

Steps: write a short script; gather materials; record each part on a phone held steady (landscape, good light, quiet room); record the voice clearly; copy the clips to a computer.

Making it 3 minutes: in the editor, trim pauses and repeated sentences from each clip, keep only one example, shorten the construction part, then join the clips in order, add titles, and export as an MP4 file.

Worksheet to print (PDF, 4 pages) Answer key for teachers

Practice every question in the book, and keep track of the ones you miss →