Information and Communication Technology - Note [Class 9]

Posted on Sunday, February 1, 2026

Unit 13

Information and Communication Technology

Information and communication technology is a medium which can store large amount of information, process data and communicate information by the help of electronic devices.

To communicate information over long distances quickly, ICT uses advanced technologies such as artificial satellites.

- Artificial satellite: Artificial satellite is defined as a body placed in orbit round the earth or moon or another planet in order to collect information or for communication.

- The first artificial satellite in the world was Sputnik-1 launched by Soviet Union on October 4, 1957.

Q. How are artificial satellites launched and maintained in orbit around the Earth?

Artificial satellites are launched using rockets and placed at a fixed height and speed so that Earth’s gravity keeps them moving in orbit. Since there is almost no air in space, satellites do not need extra energy to keep moving.

- Orbits of artificial satellite: Based on height and purpose, satellites are placed in three main orbits.

[A] Low earth orbit (LEO): Low Earth Orbit (LEO) is an orbit around the Earth at an altitude between about 180 km and 2,000 km above the Earth’s surface. Example of satellite in this orbit are ISS (international space station), Nepali sat-1 etc.

The satellites placed in LEO possesses following characteristics:

· Satellites revolve very close to the Earth

· They have a very high orbital speed

· They complete one revolution in a short time (about 90 minutes)

· They remain above a particular place on Earth for a short duration

· One satellite can observe many different places in a single day

Q. How can LEO satellites observe many places in one day?

LEO satellites revolve very fast around the Earth and continuously change their position. Due to this, they can observe many different places on Earth in a single day.

[B] Medium earth orbit (MEO): Medium Earth Orbit (MEO) is the region of space between Low Earth Orbit and Geostationary Earth Orbit, at an altitude of about 2,000 km to 35,786 km above the Earth’s surface. Examples of satellite in this orbit are navigation satellites, GPS satellites etc.

The satellites placed in MEO possesses following characteristics:

· Satellites revolve at a moderate distance from the Earth

· Their orbital speed is slower than LEO satellites

· The time period of revolution is about 12 hours

· Each satellite covers a large portion of the Earth

Q. Why are many satellites needed for GPS?

Many satellites are needed for GPS to cover all parts of the Earth so that location can be found accurately from anywhere on Earth.

[C] Geostationary earth orbit (GEO): Geostationary Earth Orbit (GEO) is a special orbit at an altitude of 35,786 km above the Earth’s equator.

Characteristics of satellites placed in GEO:

· Satellites revolve above the equator

· The time period of revolution is exactly equal to Earth’s rotational period (23 h 56 min 4 s)

· Satellites appear stationary relative to the Earth

· One satellite can continuously cover the same area of Earth

Q. Why do GEO satellites look stationary?

GEO satellites look stationary because they revolve around the Earth with the same speed as the Earth’s rotation.

Q. Why have many countries of the world launched communication satellites in geostationary orbit?
Many countries place communication satellites in geostationary orbit because these satellites appear stationary relative to the Earth. This allows them to provide continuous and reliable communication to the same area without needing to constantly track their position.

- Uplink and Downlink (Satellite Communication)

Communication between Earth and satellite happens using microwaves:

Uplink: Signal sent from ground station → satellite

Downlink: Signal sent from satellite → Earth

The satellite receives the signal, amplifies it, and sends it back.

Q. Why are satellites useful for communication?

Satellites are useful for communication because they can receive signals from one place and transmit them quickly to very far places on the Earth quickly.

NepaliSat-1 (First Satellite of Nepal)

NepaliSat-1 is the first artificial satellite of Nepal. It is an important achievement for Nepal in the field of space science and technology.

Basic Information

Type: Cube nano-satellite
Mass: 1.33 kg
Launch date: April 18, 2019
Launch place: Virginia, USA
Orbit: Low Earth Orbit (LEO)
Height from Earth: About 400 km

Motion and Visibility

It completes one revolution around the Earth in about 90 minutes.
It is visible over Nepal for about 6–10 minutes during each pass.

Constructed By

Aavash Maskey
Hariram Shrestha

Purpose of NepaliSat-1

The main purpose of NepaliSat-1 is to take photographs of Nepal from space. These photographs help in studying:

Geographical structures
Forests
Glaciers
Mountains
Streets and settlements of Nepal

Importance

Helps Nepal enter satellite technology
Provides useful geographical data
Develops scientific and technical skills

Use of Information & Communication Technology:

Magazine: Used to gain general knowledge and information about current events.
Radio: Used to receive news and educational programs quickly over long distances.
Television: Used to watch educational programs and live events happening around the world.
Telephone: Used to communicate voice messages instantly with people at distant places.
Fax: Used to send printed documents and pictures from one place to another.
Mobile Phone: Used to communicate wirelessly through calls, messages, and internet services.
Internet: Used to search information related to study and daily life.
Wi-Fi: Used to connect devices to the internet without using wires.
GPS: Used to find the exact location and direction of a place.

Telecommunication

- Telecommunication is a system in which a communication signal is transferred from one place to another using various types of technologies through wire, optical fiber, wave etc.

- Example: Telephone, fax, mobile phone, internet broadcasting through radio and television etc.

- A basic telecommunication system has following three parts:

i) Transmitter:

Receives the input information (voice, image, data)
Converts it into an electrical signal
Produces the broadcasting signal
Examples of transmitter devices: Microphone, Camera, Computer transmitter unit etc.

ii) Broadcasting channel: This is the medium through which the signal travels. Channels may be: Radio waves, Microwave beams, Metallic cables, Optical fiber etc. The signal is carried from transmitter to receiver through the channel.

iii) Receiver: It receives the transmitted signal and converts it back into useful form (sound, picture, data). Examples of receivers: Antenna, Radio set, Television, Mobile phone etc.

- In flow diagram: (VVI)

Telecommunication system flow diagram showing input signal, transmitter, broadcasting channel, receiver and output signal

Figure: Working principle of telecommunication system (Input → Transmitter → Channel → Receiver → Output)

Modulation and Demodulation

- Modulation is defined as the process of superimposing a low-frequency signal on a high-frequency carrier signal to travel it to a longer distance.

- Demodulation is defined as the process of recovering the original information-carrying signal from a modified carrier wave.

- Difference between Amplitude Modulation and Frequency modulation:(VVI)

Basis	Amplitude Modulation (AM)	Frequency Modulation (FM)
Meaning	The amplitude of the carrier wave is changed.	The frequency of the carrier wave is changed.
Parameter Changed	Amplitude varies, frequency remains constant.	Frequency varies, amplitude remains constant.
Noise Effect	More affected by noise and disturbance.	Less affected by noise, clearer signal.
Sound Quality	Lower sound quality.	Better sound quality.
Use	Used in AM radio broadcasting.	Used in FM radio and TV sound transmission.

Q. Identify the modulation for broadcasting radio wave in the given figure. Write the purpose of such modulation. (VVI)

Amplitude modulation diagram showing audio signal, carrier wave and modulated AM wave Class 9 ICT

This figure explains how amplitude modulation is used to transmit audio signals in radio communication.

Ans: The modulation used for broadcasting radio waves in the given figure is Amplitude Modulation (AM).

Purpose of such modulation:

To transmit low-energy information signals (sound) over long distances.
To convert the message signal into a form suitable for radio-wave transmission.
To make communication possible through a broadcasting channel efficiently.

Q. ‘Internet communication is a modern communication technology.’ Clarify this statement with examples.

Answer:
Internet communication is a modern communication technology because it allows people to exchange information very quickly through the world’s largest computer network. Using internet service, we can connect computers and smartphones and receive information from internet-connected devices. It is widely used today for modern communication and online services.

Examples of internet communication:

Sending and receiving messages through email
Searching learning materials using search engines like Google, Yahoo, and Bing
Using internet applications for communication and entertainment
Accessing different online services easily

Thus, internet communication is called modern communication technology because it is fast, reliable, and widely used in daily life.

Q. How do we get knowledge and information by the use of internet? Explain with examples.

Ans: The internet helps us to get knowledge and information very quickly. We can search and learn many things using the internet.

Examples:

Searching study materials on Google
Reading news and useful information online
Sending messages through email

Thus, the internet is a modern and useful way to gain knowledge.

- Search Engine: It is a software system which searches the information contained in a webpage from the internet and presents all the relevant information searched by a person. Eg: Google, Bing etc.

- Online Security: Online security is defined as step taken by people to secure their networks and computers connected to the internet.

-For the sake of Online security, following measures can be taken:

Use strong, unique passwords and enable MFA/2FA for extra protection.
Keep your software updated
Watch out for phishing emails or links
Use a VPN on public Wi-Fi to secure your data

-Cyberbullying: Cyberbullying is defined as the activity which create mental tension by using electronic devices like mobile, phone, computer, tablets etc by the medium of internet. Eg: Harassment of publishing personal information, spreading rumors about person online etc.

- Following measures can be taken to protect people from cyberbullying:

We shouldn't accept unknown persons friend request in social media.
Personal things and private information shouldn't be shared while we talk and send messages.
Photos and other information shared in social media needs to be secure.
If any person starts the activities of cyberbullying, we should inform guardians or Police.

- Digital footprint awareness:Digital footprint is data evidence generated in various electronic devices while using internet.

Q. Why should we clear cache and browsing history, and why should we avoid saving passwords on other devices?

Ans: The details of the websites remain safe in the devices, which use the internet facilities. Similarly, the password also can remain saved. To remove such data we need to clear cache files opening history of the browser. We should not click the save button if the notification "Do you want to save password?" comes in other devices except personal devices. If a password is saved, it might be misused through the data collector.

Difference between Firewall and Antivirus

Firewall	Antivirus
A firewall protects the computer by controlling incoming and outgoing network traffic.	Antivirus protects the computer by detecting and removing viruses and malware.
It acts as a security wall between the computer and the internet.	It scans files and programs to find harmful software.
It mainly prevents unauthorized access from hackers.	It mainly prevents damage caused by viruses, worms, and trojans.
Example: Windows Firewall	Example: Avast, Norton Antivirus, Kaspersky

Materials Used in Agriculture - Note [Class 9]

Posted on Sunday, January 4, 2026

Unit 19

Materials used in Agriculture

On the basis of fulfillment of food requirements, living creatures are divided into two types:

i) Autotrophs

ii) Heterotrophs

- Autotrophs: The organisms which can synthesize their own food from carbon dioxide, water and sunlight are called autotrophs. All green plants are autotrophs.

- Heterotrophs: The organisms which cannot synthesize their own food are called heterotrophs. Human beings, animals are heterotrophs.

How do we get food?

1. Agriculture: The growing of plants or crops to obtain food is called agriculture.

2. Animal Husbandry: The branch of agriculture concerned with animals that are raised for meat, milk, fiber and other products is called animal husbandry.

- Crops: The plants grown and cared in the field for getting food are known as crops. Eg: Grains, vegetables, fruits etc.

- Plant Nutrients: The minerals required by plants for its growth and survival are called plant nutrients. There are two types of plant nutrients:

i) Macronutrients

ii) Micronutrients

- Macronutrients: The mineral element needed by the plants in large amounts are called macronutrients. Eg: Carbon, Hydrogen, Oxygen, Nitrogen, Phosphorous, Potassium, Calcium, Magnesium, Sulphur etc.

- Micronutrients: The mineral element needed by the plants in very small amounts are called micronutrients. Eg: Manganese, Iron, Copper, Zinc, Boron, Chlorine, Molybdenum etc.

A split image whose one side could show a close-up of a healthy, robust plant or a bountiful harvest, representing the positive outcome of using ferlilizers and pesticides in Agriculture while the other side could subtly include visual cues related to the topic such as a stylized graphic of a plant root system being nourished or a visual representation of pest control that isn't graphic or overly detailed about the application itself with the key of image being to show the result or concept rather than the act of applying the substances.

- Soil: The upper layer of the earth crust in which plants are grown is called soil.

Function of soil for the growth of plant

It provides plant nutrients.
It provides water through the roots.
It provides oxygen to the roots through aeration.
It holds or supports the plant.
It provides humus.

Agricultural Practices

Preparation of Soil: Soil is prepared in three steps viz. Ploughing, levelling and manuring.
Sowing: Sowing is process of scattering or putting seeds in the soil for growing crop plants. It can be done either by hand or using seed drill. Also, the seedlings are transferred from nursery to main field in this process which is known as transplantation.
Use of Fertilizer : Organic and chemical fertilizers are used.
Irrigation: Irrigation is process of supplying water to crops. Water is supplied by canals, reservoir etc.
Control of weed: Unwanted plants from crop field are removed here.
Use of pesticides: They are used to control pests in crops.
Harvesting: Cutting and gathering of matured food crops is harvesting.
Threshing and Winnowing: Threshing means beating grains out of harvested crops. Winnowing is separation of grain from chaff and hey with the help of wind.

Fertilizer

- Fertilizers are the substances which are used to increase the fertility of soil for the good growth of plants. There are two types of fertilizer in general:

i) Organic fertilizer

ii) Chemical fertilizer

- Organic fertilizer: The fertilizer made by the action of bacteria and fungi over the animal wastes and plant buried into the soil is called organic fertilizer. Eg: Powder of mustard cake, bone meal, ash etc. Organic fertilizer are also of two types:

Compost fertilizer: It is natural substance obtained by the decomposition of animal waste like animal dung, human wastes and plant residue, which supplies plant nutrients and humus to the soil.
Advantages of compost fertilizer:

It doesn’t change the acidity and alkalinity of soil.

It consists of organic substance which helps in good growth of plant.

It preserves water in the soil.

It prevents erosion and leaching.

It is biodegradable and doesn’t pollute the environment.

Green fertilizer: Fertilizer obtained by decomposition of green plants in the soil of the field is called Green fertilizer. Eg: leaves of Adhatoda (asuro), Mugwort (Tite-pati), Marijuana (Ganja) etc.

- Chemical fertilizer: A salt or an organic compound containing necessary plant nutrients like nitrogen, phosphorous or potassium is called chemical fertilizer.

- Difference between Compost fertilizer and Chemical fertilizer:

Compost Fertilizer	Chemical Fertilizer
1. Compost fertilizer is prepared from decomposed organic waste.	1. Chemical fertilizer is manufactured using chemical processes.
2. It improves soil structure and fertility.	2. It increases crop yield quickly.
3. Nutrients are released slowly.	3. Nutrients are released quickly.
4. It is environment-friendly.	4. Excessive use may harm the environment.
5. It is cheaper and can be prepared at home.	5. It is costlier and must be purchased.
6. Example: Farmyard manure, vermicompost.	6. Example: Urea, DAP, NPK.

NPK Fertilizer

- NPK fertilizers are three component fertilizers providing nitogen, phosphorous and potassium. There are two types of NPK fertilizers- Compound NPK fertilizers & Blended NPK fertilizers.

🌱 Nitrogenous Fertilizers

Urea — NH₂–CO–NH₂
Ammonium Nitrate — (NH₄)NO₃
Ammonium Sulfate — (NH₄)₂SO₄

🌿 Importance of Nitrogen in Plants

Essential for the manufacture of proteins, protoplasm, and chlorophyll.
Increases the rate of plant growth.
Helps in storage of proteins and synthesis of large amounts of chlorophyll.

⚠️ Effects of Nitrogen Deficiency

Plant growth stops and crop production decreases.
Leaves turn yellow.
Flowers do not bloom properly.
Fruits and seeds become small.

🧬 Phosphorus Fertilizers

Single Super Phosphate (SSP) — Ca(H₂PO₄)₂
Triple Super Phosphate (TSP) — 3Ca(H₂PO₄)₂
Ammonium Phosphate (DAP) — (NH₄)₃PO₄

⚡ Importance of Phosphorus in Plants

Essential for root development and early plant growth.
Helps in energy transfer and storage (ATP formation).
Promotes flowering, fruiting, and seed formation.

⚠️ Effects of Phosphorus Deficiency

Poor root growth and delayed maturity.
Leaves may turn dark green or purplish.
Reduced flowering and fruit formation.
Low crop yield.

🛡️ Potassium Fertilizers

Muriate of Potash (MOP) — KCl
Sulfate of Potash (SOP) — K₂SO₄
Potassium Nitrate — KNO₃

💧 Importance of Potassium in Plants

Regulates water balance and opening–closing of stomata.
Improves disease resistance and stress tolerance.
Enhances quality of fruits, grains, and seeds.

⚠️ Effects of Potassium Deficiency

Yellowing or scorching of leaf margins.
Weak stems and lodging of plants.
Poor fruit quality and reduced yield.
Reduces immune power of plant.

Disadvantages of Overuse of Chemical Fertilizer

Overuse of chemical fertilizer changes nature of soil. Either the soil becomes too acidic or too alkaline.
Overuse of chemical fertilizer pollutes the water and make unfit for human consumption.
Overuse of chemical fertilizer kills the aquatic animals like fish.

Pesticides

- The poisonous substance used to remove, destroy, kill or control harmful pest like rodents, insects, mites, fungi, bacteria, virus is called pesticides.

- Pesticides are of different types - Insecticides, fungicide, rodenticide, herbicide etc.

- Insecticides: The chemical compounds that are used to kill or control harmful insects are called insecticides. They are of two types:

i) Bio-Insecticides

ii) Chemical Insecticides

- Bio-Insecticides: The insecticides made from natural substances to kill or control insects are called bioinsecticides. Eg: Ash, Adhatoda, Neem leaves etc.

- Chemical Insecticides: Man made chemical compounds used to kill or control harmful insects are called chemical insecticides. eg: DDT, BHC etc.

- Advantages of Bioinsecticides:

It is pollution free.
It has no harmful effect on human and crop.
It is biodegradable.

- Disadvantages of Chemical insecticides:

It pollutes water which harms aquatic organisms.
Contact with chemical insecticide effects the nervous system and glandular system in human,
Effects growth and reproductive capacity of birds and fishes.
Promotes respiratory diseases.
It not only kill harmful insects but also kill useful insect.

- Precautions while using chemical insecticides:

1. Manual for using insecticide should be studied properly.

2. Suitable cloth, mask and gloves should be used while spraying the insecticide.

3. Insecticide should not come in contact with eye and mouth.

4. Insecticide should be spread in the direction of air.

5. The equipment used to spray insecticide should be washed properly after its use.

6. Hand should be washed properly after handling the equipment.

- Conservation of soil quality:

1. Frequent test of quality of soil.

2. Use of suitable farming technology like:

(i) Crop rotation

(ii) Multiple cropping

(iii) Maximum use of organic fertilizer

(iv) Minimum use of chemical fertilizer

(v) Suitable irrigation technology

3. Proper use of land

Activities

1. Chemical fertilizers and pesticides used in farming have caused negative effects on human health. Write any five slogans to create awareness about this issue.

2. Farmers are confused about whether to use chemical fertilizers to increase crop production or not. What suggestions would you give to them?