Our Changing Earth

1. Answer the following questions

(i) Why do the plates move?
The plates move because of the movement of molten magma inside the Earth’s mantle. This molten magma moves in a circular manner (convection currents), which pushes and pulls the lithospheric plates very slowly — just a few millimetres each year.

(ii) What are exogenic and endogenic forces?

• Endogenic forces are forces that act in the interior of the Earth. They can be sudden (earthquakes, volcanoes, landslides) or slow (mountain building).

• Exogenic forces are forces that work on the surface of the Earth, caused by external agents like rivers, wind, sea waves, and glaciers. They include erosion and deposition.

(iii) What is erosion?
Erosion is the wearing away of the landscape by natural agents such as water, wind, and ice. The eroded material is transported and deposited elsewhere.

(iv) How are flood plains formed?
When a river overflows its banks during floods, it deposits layers of fine soil and sediments along both sides of its channel. Over time, this deposition creates a flat fertile area called a flood plain.

(v) What are sand dunes?
Sand dunes are low hill-like structures formed in deserts when the wind deposits sand in one place after carrying it over a distance.

(vi) How are beaches formed?
Beaches are formed when sea waves deposit sand, pebbles, and sediments along the shoreline.

(vii) What are ox-bow lakes?
Ox-bow lakes are curved lakes formed when a meander in a river is cut off from the main channel due to continuous erosion and deposition.

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2. Tick the correct answer

(i) Which is not an erosional feature of sea waves?
✅ (b) Beach

(ii) The depositional feature of a glacier is:
✅ (c) Moraine

(iii) Which is caused by the sudden movements of the earth?
✅ (a) Volcano

(iv) Mushroom rocks are found in:
✅ (a) Deserts

(v) Ox bow lakes are found in:
✅ (b) River valleys

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3. Match the following

Column A	Column B
(i) Glacier	(c) River of ice
(ii) Meanders	(d) Rivers
(iii) Beach	(a) Sea shore
(iv) Sand dunes	(h) Deserts
(v) Waterfall	(g) Hard bed rock
(vi) Earthquake	(e) Vibrations of earth

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4. Give reasons

(i) Some rocks have a shape of a mushroom.
In deserts, wind erodes the lower part of a rock more than the upper part because the sand particles carried by wind mostly hit the base. This creates a narrower base and a wider top, forming a mushroom shape.

(ii) Flood plains are very fertile.
During floods, rivers deposit fine soil, silt, and other minerals on the flood plain. This nutrient-rich sediment makes the soil highly fertile.

(iii) Sea caves are turned into stacks.
Sea waves first form caves in coastal rocks. Continuous erosion enlarges these caves into arches. Eventually, the roof of the arch collapses, leaving behind an isolated vertical wall called a stack.

(iv) Buildings collapse due to earthquakes.
Earthquakes produce strong vibrations that travel through the ground. If buildings are not designed to withstand these vibrations, the shaking causes structural damage, leading to collapse.

Major Landforms of the Earth

Major Landforms of the Earth

The surface of the Earth is constantly being shaped and reshaped by natural processes. Two key processes are responsible for changing the landscape:

1. Weathering – The breaking down of rocks into smaller pieces by natural forces such as temperature change, plants, animals, and chemicals.

2. Erosion – The wearing away of the landscape by moving agents such as water, wind, and ice.

After erosion, the eroded material is transported by these agents and eventually deposited elsewhere. The combined effect of erosion and deposition creates various major landforms.

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1. Work of a River

Rivers shape the land in three stages – upper course (erosion), middle course (erosion & deposition), and lower course (deposition).

A. Waterfalls

• Formed when a river flows over hard rock followed by softer rock, causing the softer rock to erode faster.

• Waterfalls are steep drops in the river’s course.

• Examples:

  • Angel Falls – Venezuela (Highest in the world)

  • Niagara Falls – On the Canada–USA border

  • Victoria Falls – On the Zambia–Zimbabwe border

B. Meanders and Ox-bow Lakes

• Meander: Large bends formed by a river in its middle and lower course due to lateral erosion.

• Over time, erosion on the outer banks and deposition on the inner banks make the loop sharper.

• Eventually, the loop is cut off, forming an ox-bow lake.

C. Floodplains and Levees

• During floods, rivers overflow their banks and deposit fertile alluvial soil, creating floodplains.

• Raised banks of deposited material along the river are called levees.

D. Delta Formation

• At the river’s mouth, speed decreases, and the river splits into distributaries.

• Deposition at the mouths forms a triangular or fan-shaped delta.

• Example: The Ganga–Brahmaputra Delta.

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2. Work of Sea Waves

Sea waves continuously erode and deposit material along coastlines, creating distinct coastal landforms.

• Sea Caves: Formed when waves erode cracks in coastal rocks.

• Sea Arches: When waves erode through a cave, leaving an arch-shaped opening.

• Stacks: When the roof of a sea arch collapses, leaving an isolated vertical rock column.

• Sea Cliffs: Steep rocky coasts rising sharply from the sea.

• Beaches: Formed when sea waves deposit sand and pebbles along the shore.

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3. Work of Ice (Glaciers)

Glaciers are “rivers of ice” that move slowly but have powerful erosive force.

• They erode by bulldozing soil and rocks, carving out deep hollows.

• When the ice melts, these hollows become lakes.

• Deposited material (rocks, gravel, sand) forms glacial moraines.

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4. Work of Wind

Wind is an active erosional and depositional agent in desert regions.

• Mushroom Rocks: Formed when wind erodes the lower parts of a rock faster than the upper parts, creating a narrow base and wider top.

• Sand Dunes: Low hills of sand formed by wind deposition.

• Loess: Fine, light sand particles carried over long distances and deposited in thick layers.

  • Example: Large loess deposits in China.

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5. Summary Table – Agents of Landform Formation

Agent	Erosional Landforms	Depositional Landforms
River	Waterfalls, Meanders	Floodplains, Levees, Delta
Sea Waves	Sea Caves, Arches, Stacks, Cliffs	Beaches
Glaciers	Glacial valleys, hollows	Moraines
Wind	Mushroom rocks	Sand dunes, Loess

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Conclusion

The Earth’s surface is in a state of continuous transformation. Rivers, sea waves, glaciers, and wind constantly modify the landscape through erosion, transportation, and deposition. These processes give rise to spectacular natural features, many of which have significant economic, environmental, and cultural value.

Chapter 3 – Earth Movements and Earthquakes

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Chapter 3 – Earth Movements and Earthquakes

1. The Lithosphere and Lithospheric Plates

The lithosphere is the solid outermost shell of the Earth, which includes the crust and the uppermost part of the mantle. Interestingly, the lithosphere is not a single unbroken sheet; instead, it is broken into a number of large and small pieces called lithospheric plates.

• These plates are like giant puzzle pieces covering the surface of the Earth.

• They are in slow motion—moving only a few millimetres per year.

Reason for movement:
Beneath the lithosphere lies molten magma in the mantle. This magma moves in a circular pattern (convection currents). The heat from Earth’s interior causes this molten rock to rise, move laterally, and then sink again, dragging the lithospheric plates along with it.

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2. Forces Causing Earth Movements

Movements on Earth’s surface are the result of two main types of forces:

A. Endogenic Forces (Internal forces)

These originate inside the Earth and cause changes on the surface.
They are of two types:

1. Sudden Forces – Act very quickly, causing immediate changes:

   • Earthquakes

   • Volcanoes

   • Landslides

2. Diastrophic Forces – Act very slowly over thousands or millions of years:

   • Mountain Building (e.g., formation of the Himalayas)

   • Plateau formation

B. Exogenic Forces (External forces)

These work on the surface of the Earth due to agents like:

• Rivers

• Wind

• Sea waves

• Glaciers

They cause erosion (wearing away of land) and deposition (laying down of material).

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3. Sudden Movements – Volcanoes and Earthquakes

A. Volcano

A volcano is a vent or opening in the Earth’s crust through which molten material (lava), ash, and gases escape from beneath the surface.

• Eruptions may be explosive or quiet.

• They can alter landscapes dramatically and cause widespread destruction.

B. Earthquake

An earthquake is the shaking or trembling of the Earth’s surface caused by the sudden movement of lithospheric plates.

Key Terms:

• Focus: The location inside the Earth where the earthquake originates.

• Epicentre: The point on Earth’s surface directly above the focus.

• Seismic waves: Vibrations that travel outward from the focus and epicentre.

Damage pattern:
The strongest shaking and most severe damage occur nearest to the epicentre, and the intensity decreases as you move away.

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4. Types of Earthquake Waves

1. P Waves (Primary or Longitudinal Waves)

   • Travel fastest.

   • Can move through solids, liquids, and gases.

   • Cause particles to move back and forth in the direction of the wave.

2. S Waves (Secondary or Transverse Waves)

   • Slower than P waves.

   • Can travel only through solids.

   • Move particles up and down or side to side, perpendicular to the wave’s direction.

3. L Waves (Surface Waves)

   • Travel along Earth’s surface.

   • Cause the most damage due to rolling and swaying motion.

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5. Measuring Earthquakes

• Instrument: Seismograph – records the intensity and duration of vibrations.

• Scale: Richter Scale – measures magnitude.

Richter Scale guide:

• 2.0 or less: Barely felt.

• Over 5.0: Damage possible (falling objects, cracks).

• 6.0 and above: Very strong, structural damage likely.

• 7.0 or more: Major earthquake, widespread destruction.

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6. Earthquake Prediction

Although exact prediction is not possible, certain traditional indicators have been observed:

• Sudden change in animal behaviour – fish become restless, snakes emerge from their holes.

• Groundwater level fluctuations.

• Unusual sky glows or sounds.

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7. Earthquake Preparedness

Preparedness can save lives and reduce damage.

Safe Spots during an earthquake:

• Under a sturdy table, kitchen counter, or desk.

• Against an inside wall or corner.

Places to avoid:

• Near fireplaces, chimneys, windows, mirrors, or picture frames.

Other precautions:

• Spread awareness among friends and family.

• Conduct drills to know how to react.

• Keep an emergency kit ready (water, torch, first-aid).

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8. Summary Table

Force Type	Nature	Examples
Endogenic	Internal	Earthquakes, Volcanoes, Mountain building
Exogenic	External	River erosion, Wind deposition, Glacial action

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Conclusion

The Earth’s surface is dynamic and constantly changing due to internal (endogenic) and external (exogenic) forces. Understanding how lithospheric plates move and how earthquakes occur helps us reduce damage through preparedness and awareness. While we cannot stop these natural processes, we can certainly learn to live more safely with them.

THREE MAIN COMPONENTS OF THE CIRCULATORY SYSTEM

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🫀 THREE MAIN COMPONENTS OF THE CIRCULATORY SYSTEM

(New Zealand Curriculum – Study Material) Name of the Student : SARAH

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1️⃣ HEART – The Pump of the System

Function:
The heart is a muscular organ that works as a pump to circulate blood throughout the body. It keeps blood moving continuously, supplying oxygen and nutrients and removing waste.

Key Facts:

• Has four chambers – right atrium, right ventricle, left atrium, left ventricle

• Left side pumps oxygenated blood to the body

• Right side pumps deoxygenated blood to the lungs

• Beats about 70–75 times per minute on average

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2️⃣ BLOOD VESSELS – The Pathways

Function:
Blood vessels are the network of tubes that carry blood to and from the heart and throughout the body.

Types of Blood Vessels:

Vessel Type	Function
Arteries	Carry blood away from the heart (usually oxygen-rich)
Veins	Carry blood toward the heart (usually oxygen-poor)
Capillaries	Very thin vessels where exchange of gases, nutrients, and waste takes place between blood and cells

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3️⃣ BLOOD – The Transport Fluid

Function:
Blood is the fluid that carries essential substances throughout the body.

Components of Blood:

Component	Function
Red Blood Cells (RBCs)	Carry oxygen using haemoglobin
White Blood Cells (WBCs)	Fight infections (part of immune system)
Platelets	Help in clotting to stop bleeding
Plasma	The liquid part that carries nutrients, hormones, and waste

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✅ Summary Table

Component	Role
Heart	Pumps blood
Blood Vessels	Carry blood throughout the body
Blood	Transports oxygen, nutrients, waste, and fights infection

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ROLE OF THE CIRCULATORY SYSTEM

 🫀 ROLE OF THE CIRCULATORY SYSTEM

(Grade 10 – New Zealand Curriculum Study Notes)  Name of the Student : SARAH

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🌐 What is the Circulatory System?

The circulatory system is the transport system of the human body. It is responsible for moving blood, nutrients, oxygen, carbon dioxide, and hormones to and from the cells.

It is made up of three main parts:

1. Heart

2. Blood Vessels (arteries, veins, capillaries)

3. Blood

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💡 Key Functions of the Circulatory System

Function	Description
Transporting Oxygen	Delivers oxygen from the lungs to all body cells through red blood cells.
Transporting Nutrients	Carries nutrients from the digestive system to body cells.
Removing Waste Products	Carries carbon dioxide to the lungs and waste products to the kidneys.
Circulating Hormones	Distributes hormones from glands to organs to control body functions.
Protecting the Body	White blood cells fight infection; platelets help in clotting.
Regulating Body Temperature	Helps maintain constant internal temperature (homeostasis).

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🫀 Role of the Heart

• Acts as a pump that pushes blood around the body.

• Has four chambers: left atrium, left ventricle, right atrium, right ventricle.

• Pumps oxygenated blood to the body and deoxygenated blood to the lungs.

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🩸 Role of Blood Vessels

Type	Role
Arteries	Carry oxygen-rich blood away from the heart.
Veins	Carry oxygen-poor blood towards the heart.
Capillaries	Tiny vessels where gas and nutrient exchange occurs between blood and cells.

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📌 Summary

The circulatory system ensures that every cell in the body gets the oxygen and nutrients it needs and that waste products are removed efficiently. It also plays a protective and regulatory role, keeping the internal environment stable.

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LIST OF ORGANELLES, TISSUES, ORGANS, ORGAN SYSTEMS

Curriculum-friendly list of all organelles, tissues, organs, and organ systems, suitable for Grade 10 New Zealand students:  Name of the Student : SARAH

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🧫 LIST OF ORGANELLES

(Found inside cells, both plant and animal)

Organelle	Function
Nucleus	Controls cell activities; contains DNA
Mitochondria	Produces energy (ATP) through respiration
Ribosomes	Make proteins
Endoplasmic Reticulum (ER)	Transports substances; two types – Rough (with ribosomes) and Smooth
Golgi Apparatus	Packages and sends proteins
Lysosomes	Break down waste and old cell parts
Vacuole	Stores water, nutrients, and waste (larger in plant cells)
Chloroplasts	Carries out photosynthesis (plant cells only)
Cell Membrane	Controls what enters and leaves the cell
Cytoplasm	Jelly-like fluid where reactions occur
Cell Wall	Provides structure and protection (plant cells only)
Centrioles	Help in cell division (animal cells only)

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🧵 LIST OF TISSUES

In Animals:

Tissue Type	Function
Epithelial Tissue	Covers body surfaces and organs
Muscle Tissue	Contracts to produce movement
Nervous Tissue	Carries signals (nerve impulses)
Connective Tissue	Supports, binds, or separates organs and tissues (includes blood, fat, bone, cartilage)

In Plants:

Tissue Type	Function
Xylem	Transports water from roots to leaves
Phloem	Transports sugars (food) from leaves to rest of the plant
Parenchyma	Stores food and performs photosynthesis
Collenchyma	Provides flexible support
Sclerenchyma	Provides rigid support

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🫁 LIST OF ORGANS

In Humans/Animals:

Organ	Function
Heart	Pumps blood
Lungs	Gas exchange (O₂ in, CO₂ out)
Brain	Controls bodily functions and thinking
Stomach	Breaks down food
Liver	Processes nutrients and detoxifies
Kidneys	Filters blood and makes urine
Skin	Protects the body and regulates temperature
Intestines	Absorbs nutrients and water
Bladder	Stores urine
Pancreas	Produces insulin and digestive enzymes

In Plants:

Organ	Function
Roots	Absorb water and nutrients
Stem	Supports plant and transports substances
Leaves	Photosynthesis
Flowers	Reproduction
Fruit	Protects and helps spread seeds

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🧬 LIST OF ORGAN SYSTEMS (In Humans)

Organ System	Major Organs Involved	Function
Circulatory System	Heart, blood vessels, blood	Transports oxygen, nutrients, and waste
Respiratory System	Lungs, trachea, bronchi	Takes in oxygen and removes carbon dioxide
Digestive System	Mouth, stomach, intestines, liver	Breaks down food and absorbs nutrients
Nervous System	Brain, spinal cord, nerves	Controls body activities and processes information
Muscular System	Muscles (skeletal, smooth, cardiac)	Movement
Skeletal System	Bones, joints	Provides structure and protects organs
Excretory System	Kidneys, bladder, skin	Removes waste from the body
Endocrine System	Glands (pituitary, thyroid, etc.)	Hormone production and regulation
Reproductive System	Testes, ovaries, uterus, penis, vagina	Reproduction
Immune System	White blood cells, lymph nodes	Protects against disease
Integumentary System	Skin, hair, nails	Protects the body and regulates temperature

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LIVING ORGANISM : GRADE 10 (NEW ZEALAND CURRICULUM)

 📘 STUDY MATERIAL FOR GRADE 10 (NEW ZEALAND CURRICULUM)

TOPIC: 🔬 DISTINGUISH BETWEEN ORGANELLE, CELL, TISSUE, ORGAN, ORGAN SYSTEM AND ORGANISM

 Name of the Student : SARAH

🧫 ORGANELLE

Definition:
Organelles are tiny specialised structures found inside cells that carry out specific functions necessary for the cell to survive and function.

Examples:

• Nucleus – controls the cell's activities

• Mitochondria – produces energy

• Ribosomes – make proteins

• Chloroplasts (in plant cells) – carry out photosynthesis

Key Point: Organelles are like the organs inside a single cell.

🔬 CELL

Definition:
The basic structural and functional unit of life. All living things are made up of cells.

Types:

• Prokaryotic Cells – simple cells without a nucleus (e.g., bacteria)

• Eukaryotic Cells – complex cells with a nucleus (e.g., plant and animal cells)

Key Point: A cell contains organelles and is the smallest unit of life.

🧵 TISSUE

Definition:
A group of similar cells that work together to perform a specific function.

Examples:

• Muscle tissue – contracts to produce movement

• Nervous tissue – carries messages around the body

• Xylem tissue (in plants) – transports water

Key Point: Tissues are made of cells with a common function.

🫀 ORGAN

Definition:
A structure made up of different types of tissues that work together to perform a specific function.

Examples:

• Heart – pumps blood

• Lungs – help in breathing

• Leaf (in plants) – performs photosynthesis

Key Point: Organs are made up of tissues, and each organ has a special job in the body or plant.

🧬 ORGAN SYSTEM

Definition:
A group of organs that work together to perform a major life function.

Examples:

• Digestive system – breaks down food

• Respiratory system – helps in breathing

• Circulatory system – transports nutrients and oxygen

Key Point: Organ systems are teams of organs working for a larger function.

🧍 ORGANISM

Definition:
A complete living thing that can carry out all life processes on its own.

Examples:

• Human, Bird, Tree, Bacteria

Key Point: An organism may be made up of one cell (unicellular) or many cells (multicellular).

🧠 SUMMARY TABLE

Level	Made of...	Example
Organelle	Inside the cell	Mitochondria, Nucleus
Cell	Organelles	Muscle cell, Leaf cell
Tissue	Similar cells	Muscle tissue, Xylem
Organ	Different tissues	Heart, Leaf
Organ System	Organs	Respiratory system
Organism	Organ systems (or single cell)	Human, Tree, Amoeba

✅ REMEMBER:
Smallest to Largest → Organelle → Cell → Tissue → Organ → Organ System → Organism

AC Generator

Note on the AC Generator, written specifically for a Grade 12 Australian Physics student based on the Australian Curriculum (Stage 6 – NSW, or Year 12 Physics Units):

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📘 AC Generator (Alternating Current Generator) – Step-by-Step Notes

✅ 1. What is an AC Generator?

An AC generator (Alternating Current generator) is a device that converts mechanical energy into electrical energy using electromagnetic induction.

📌 Key principle: Based on Faraday’s Law of Electromagnetic Induction

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✅ 2. How It Works – Step-by-Step Process

⚙️ Step 1: Setup – The Basic Components

An AC generator typically has:

• A coil (armature): Wire loop(s) that rotate

• Magnetic field (B): Provided by permanent magnets or electromagnets

• Slip rings and brushes: Maintain contact with the rotating coil

• External circuit: Where current flows

🧠 Think of a copper wire coil spinning inside a magnetic field.

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⚡ Step 2: Rotation of the Coil

• The coil is mechanically rotated (e.g., by a turbine or hand crank).

• As the coil spins, the angle between the magnetic field (B) and the coil changes continuously.

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💡 Step 3: Induction of EMF (Faraday’s Law)

As the coil rotates:

• The magnetic flux through the coil changes.

• This changing magnetic flux induces an EMF (voltage) in the coil.

📘 Faraday’s Law:

$$\text{EMF} = -N \frac{d\Phi}{dt}$$

Where:

• $N$ = number of turns

• $\Phi$ = magnetic flux = $B \cdot A \cdot \cos(\theta)$

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🔁 Step 4: Alternating Current (AC) is Produced

• As the coil spins 360°, the direction of the current reverses every half-turn.

• This creates alternating current (AC):

  • Positive in one half of the cycle

  • Negative in the other half

🌀 One complete revolution = one AC cycle (or waveform)

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✅ 3. Waveform of AC

• The voltage generated varies sinusoidally.

• Graph shape: Sine wave

• Key terms:

  • Peak voltage (Vmax): Maximum voltage

  • Frequency (f): Number of cycles per second (Hz)

  • Period (T): Time for one complete cycle $T = \frac{1}{f}$

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✅ 4. Energy Conversion

• Input: Mechanical energy (e.g., from wind, water, or steam)

• Output: Electrical energy (AC)

🔄 Energy transformation:
Mechanical → Electrical (through magnetic field)

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✅ 5. Practical Example

• Power stations use massive AC generators:

  • Hydroelectric

  • Wind turbines

  • Thermal (coal/gas-fired)

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✅ 6. Role of Slip Rings and Brushes

• Slip rings are attached to the rotating coil.

• Brushes press against the slip rings to conduct current to the external circuit.

• Allows continuous rotation without twisting wires.

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✅ 7. Differences from DC Generator

Feature	AC Generator	DC Generator
Current type	Alternating	Direct
Slip rings	Yes	No (uses split-ring commutator)
Output	AC	DC
Applications	Power stations	Batteries, motors

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✅ 8. Applications of AC Generators

• Household electricity supply

• Electric power grids

• Renewable energy systems (wind, hydro)

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✅ 9. Important Formulae

1. Magnetic Flux:

$$\Phi = B \cdot A \cdot \cos(\theta)$$

2. Induced EMF (single loop):

$$\text{EMF} = B \cdot A \cdot \omega \cdot \sin(\omega t)$$

Where:

• $\omega$ = angular velocity = $2\pi f$

3. General EMF (N loops):

$$\text{EMF} = N B A \omega \sin(\omega t)$$

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✅ 10. Summary (At a Glance)

Concept	Description
Device	AC Generator
Converts	Mechanical → Electrical
Law Used	Faraday’s Law
Output	Alternating Current (AC)
Key Parts	Coil, magnets, slip rings, brushes
Output Wave	Sinusoidal (Sine wave)

🎓 Extension (HSC Physics - Depth Study Idea)

• Investigate how increasing the number of turns (N) or magnetic field strength (B) affects the output voltage.

AC Generator Animation

PART-1 : LIFE PROCESSES

🧬  What Are Life Processes?

Class Level: 9–10 | NEP Aligned | Core Concepts: Biology

🌱 Chapter 5.1 :  Definition of Life Processes

Life processes are the vital functions or maintenance activities carried out by all living organisms to sustain life. Even when an organism is at rest, these processes continue internally to keep the body functional and healthy.

⚙️ Why Are Life Processes Important?

• They maintain internal stability (homeostasis).

• They help organisms grow, reproduce, repair damage, and adapt to changing conditions.

• Without life processes, cells would break down, and life would cease.

🔋 Energy Requirement

• All life processes need energy to operate.

• This energy comes from food, which contains carbon-based molecules.

• The food must be transferred into the body (nutrition), broken down (respiration), and distributed (transportation).

🍽️ Nutrition

• It is the process of acquiring energy and raw materials from the environment.

• Organisms use various modes of nutrition depending on complexity (e.g., autotrophic in plants, heterotrophic in animals).

• Food provides carbon-based molecules necessary for building body structures and generating energy.

💨 Respiration

• After food is taken in, it must be broken down into usable energy.

• Respiration is the chemical process where glucose (or similar molecules) is broken down using oxygen, releasing energy (ATP).

• These are typically oxidation-reduction (redox) reactions.

🚛 Transport System

• In single-celled organisms: nutrients, gases, and wastes are exchanged directly with the environment by diffusion.

• In multi-cellular organisms: specialised tissues (like blood in humans) are needed to transport substances (e.g., oxygen, nutrients, waste).

• Diffusion is too slow for large, complex bodies.

🚮 Excretion

• Excretion is the process of removing waste by-products of chemical reactions.

• These wastes (like carbon dioxide, urea, etc.) can be harmful if not removed.

• Specialised excretory tissues or organs (like kidneys in humans) are responsible for this function.

🧠 Conclusion

Life processes are interlinked and collectively maintain the internal environment of organisms. As complexity increases, organisms evolve specialised systems to handle basic life activities efficiently.

📝 Worksheet: Higher Order Thinking Skills (HOTS) on Life Processes

Skills Covered: Analysis | Application | Conceptual Reasoning | Evaluation
Total Marks: 25 | Class Level: 9–10 | Time: 40 min

✍️ SECTION A: Conceptual Reasoning (2 Marks Each)

1. Why is food considered a source of both energy and raw materials for organisms?

2. Explain why energy is needed even during sleep or inactivity.

3. Why can diffusion meet the needs of unicellular organisms but not multicellular ones?

4. What role do oxidation-reduction reactions play in the generation of energy in living organisms?

5. How does specialisation of tissues help in efficient functioning in multicellular organisms?

🔍 SECTION B: Compare and Contrast (3 Marks Each)

6. Compare nutrition and respiration in terms of purpose, location, and outcome in the body.

7. Contrast the process of transportation in unicellular organisms and in humans.

🧠 SECTION C: Application and Critical Thinking (4 Marks Each)

8. A scientist finds a new large multicellular organism that lacks a transport system. Predict and explain what limitations this organism might face in its environment.

9. If excretion is blocked in an organism, what might be the short-term and long-term consequences?

💡 SECTION D: Extension Challenge (4 Marks)

10. Propose a simple design for an artificial "life process machine" that performs nutrition, respiration, and excretion. How would each part function?

🌱 Chapter 5.2 – Nutrition

📘 Topic: Life Processes – Nutrition in Organisms

✅ What is Nutrition?

Nutrition is the process by which organisms obtain and use food to produce energy, grow, and maintain body functions.
Even when we are resting, our body uses energy to maintain internal order—this energy and raw material come from food.

🔄 Why Do Organisms Need Nutrition?

Organisms need nutrition for:

• Energy (for movement, repair, and basic life functions)

• Growth and development

• Maintenance of body structure

• Synthesis of proteins and enzymes

🌿 How Do Organisms Get Their Food?

All organisms need food, but how they obtain it differs:

🌞 1. Autotrophic Nutrition (Self-feeding)

Definition: Organisms that make their own food from inorganic substances like carbon dioxide and water using sunlight as energy.
Examples: Green plants, blue-green algae, some bacteria (like cyanobacteria).

🔬 Photosynthesis – The Autotrophic Process

Photosynthesis is the process by which green plants prepare food (glucose) using:

• Sunlight

• Chlorophyll (found in chloroplasts)

• Carbon dioxide (from air)

• Water (from soil)

Equation:

$$\text{Carbon dioxide} + \text{Water} \xrightarrow{\text{Sunlight + Chlorophyll}} \text{Glucose} + \text{Oxygen}$$ $$6CO_2 + 6H_2O \xrightarrow{\text{Light}} C_6H_{12}O_6 + 6O_2$$

🧪 Steps in Photosynthesis:

1. Absorption of light energy by chlorophyll.

2. Conversion of light energy into chemical energy and splitting of water into hydrogen and oxygen.

3. Reduction of carbon dioxide into carbohydrates (glucose).

💡 Note: These steps may occur separately. For example, desert plants take up CO₂ at night and use it during the day.

🧫 Where does Photosynthesis occur?

• Takes place in the chloroplasts (contain chlorophyll) present in green parts of the plant (mainly leaves).

• Stomata (tiny pores on leaves) allow gas exchange—CO₂ in, O₂ out.

⚙️ Role of Guard Cells in Stomatal Movement:

• Open pore: Guard cells swell with water.

• Close pore: Guard cells lose water and shrink.

• Helps control water loss and CO₂ uptake.

💧 Raw Materials Required for Photosynthesis:

• Carbon dioxide from air (via stomata).

• Water from soil (via roots).

• Minerals from soil like:

  • Nitrogen (for proteins) – taken as nitrates/nitrites or from organic compounds via nitrogen-fixing bacteria

  • Phosphorus, Magnesium, Iron – for enzyme and pigment production

🧪 Example Experiments (as referred in textbook):

1. Chlorophyll is essential for photosynthesis (e.g., variegated leaf test).

2. Sunlight is essential – use a leaf partially covered with black paper and observe starch formation.

🍄 2. Heterotrophic Nutrition

Definition: Organisms that cannot make their own food and depend on other organisms for nutrition.
Examples: Animals, fungi, most bacteria.

• They break down complex food into simpler molecules using enzymes (biological catalysts).

• They depend directly or indirectly on autotrophs for survival.

🧠 Summary Chart

Nutrition Type	Organisms Involved	Food Source	Example
Autotrophic	Green plants, algae	CO₂, water, sunlight	Mango tree, Chlorella
Heterotrophic	Animals, fungi	Other organisms	Human, Mushroom

🔁 Connection with Human Nutrition

• Plants store excess glucose as starch.

• Humans store extra glucose as glycogen in muscles and liver.

✍️ Conclusion

Nutrition is essential for the survival of all living beings. Autotrophs prepare food using sunlight and provide the base of the food chain, while heterotrophs depend on them directly or indirectly. Understanding photosynthesis helps us appreciate how life is sustained on Earth.

📘 Chapter 5.2.2 & 5.2.3: Heterotrophic Nutrition & How Organisms Obtain Their Nutrition

Subject: Biology | Level: Grade 10 (NEP/CBSE)

🌱 What is Heterotrophic Nutrition?

Heterotrophic nutrition is the mode of nutrition in which organisms cannot prepare their own food and depend on other organisms (plants or animals) for survival.

🔄 Unlike autotrophs (which make food using sunlight), heterotrophs must either:

• Consume other living organisms

• Feed on dead/decaying organic matter

• Absorb nutrients from a host organism

🍽️ Types of Heterotrophic Nutrition

Type	Description	Examples
Holozoic	Ingestion of solid food and internal digestion	Human, lion, cow, Amoeba
Saprophytic	Secretes enzymes outside the body to break down food and then absorb it	Fungi (mushroom, bread mould)
Parasitic	Obtains nutrients from a living host without killing it	Cuscuta, lice, leeches, tapeworm

🧠 Adaptation in Nutrition

Different organisms are adapted to their environment and food source:

• A cow (herbivore) eats grass (stationary), has flat teeth and a long digestive tract to digest cellulose.

• A lion (carnivore) hunts prey (mobile), has sharp teeth and a short gut adapted for protein digestion.

• A parasite like Cuscuta grows on host plants and absorbs nutrients from them without killing them.

🧫 How Do Organisms Obtain Their Nutrition?

The method of food intake and digestion varies depending on:

• Body structure

• Complexity of the organism

• Type of food

🦠 Unicellular Organisms (like Amoeba & Paramoecium)

🔬 Amoeba (Holozoic Nutrition)

• Uses pseudopodia (false feet) to surround and engulf food particles.

• Forms a food vacuole where enzymes digest the food.

• Simple substances diffuse into the cytoplasm, and undigested materials are expelled out.

🔬 Paramoecium

• Has a fixed shape.

• Uses cilia (tiny hair-like structures) to sweep food to a specific spot on the cell surface.

• Food enters through the oral groove and is digested inside a food vacuole.

➡️ Both organisms carry out intracellular digestion (digestion occurs inside the cell).

🧍‍♂️ Multicellular Organisms

As complexity increases:

• Specialised organs are developed (mouth, stomach, intestine, etc.)

• Different tissues perform different functions (ingestion, digestion, absorption, assimilation, and egestion).

➡️ For example, in humans:

• Mouth: ingestion and mechanical breakdown

• Stomach: protein digestion

• Small intestine: digestion and absorption

• Large intestine: water absorption and waste formation

🔄 Summary Chart

Organism Type	Food Intake Method	Digestion Type	Example
Amoeba	Pseudopodia engulf food	Intracellular	Amoeba
Paramoecium	Cilia move food to oral groove	Intracellular	Paramoecium
Mushroom (Fungi)	External enzyme secretion	Extracellular	Bread mould, yeast
Tapeworm, Leech	Absorbs food from host	Depends on host	Parasitic organisms
Humans, animals	Ingestion & internal digestion	Extracellular	Human, cow, lion

🧠 Key Takeaways:

• Heterotrophs depend on autotrophs directly or indirectly.

• The body design, food source, and environment determine how organisms obtain and digest food.

• Unicellular organisms use simple methods like diffusion and vacuole formation, while multicellular organisms need specialised systems for digestion and absorption.

🧠  5.2.4: Nutrition in Human Beings

🔹 What is the Human Digestive System?

The human digestive system consists of a long, coiled tube called the alimentary canal that runs from the mouth to the anus, along with digestive glands that release enzymes to aid in digestion.
Each part of the canal is specialised to perform a specific function during the process of nutrition.

🔹 Key Steps in Human Nutrition:

1. Ingestion (Mouth)

• Teeth grind and crush food into smaller particles to ensure smooth passage.

• Salivary glands secrete saliva, which contains the enzyme salivary amylase (also called ptyalin) that begins the breakdown of starch into sugar.

• The tongue mixes food and helps in swallowing.

• Food is moistened to ease passage through the alimentary canal.

2. Swallowing & Peristalsis

• Food travels through the oesophagus (food pipe).

• A wave-like muscular motion called peristalsis pushes the food downward in a regulated manner throughout the canal.

🔹 Stomach – Mechanical & Chemical Digestion

• Food enters the stomach, a muscular, expandable organ.

• Gastric glands in the stomach lining secrete:

  • Hydrochloric acid (HCl) – creates an acidic medium and kills bacteria.

  • Pepsin – a protein-digesting enzyme activated in the acidic medium.

  • Mucus – protects the inner lining from acid attack.

• Acid imbalance can lead to acidity, a common digestive discomfort.

🔹 Small Intestine – Complete Digestion & Absorption

• The longest part of the digestive tract; tightly coiled to fit in limited space.

• Food moves here in small amounts due to the action of a sphincter muscle between the stomach and intestine.

Role of Digestive Secretions:

• Liver produces bile, stored in the gallbladder and released into the intestine:

  • Neutralises the acidic food from the stomach.

  • Emulsifies fats into smaller globules (like soap on grease) to aid enzyme action.

• Pancreas secretes pancreatic juice, containing:

  • Trypsin (digests proteins),

  • Lipase (digests emulsified fats),

  • Other enzymes for carbohydrate digestion.

• Intestinal glands secrete enzymes that:

  • Convert proteins → amino acids,

  • Carbohydrates → glucose,

  • Fats → fatty acids + glycerol

🔹 Absorption of Nutrients

• The inner lining of the small intestine has finger-like projections called villi:

  • Increase surface area for maximum absorption,

  • Contain blood vessels to transport nutrients to all body cells.

• Cells use these nutrients for:

  • Energy production,

  • Tissue repair,

  • Growth and maintenance.

🔹 Large Intestine – Water Absorption & Egestion

• Absorbs excess water from the undigested food.

• Remaining waste is formed into semi-solid feces.

• Elimination of waste occurs via the anus, controlled by the anal sphincter.

🧪 Important Terms

Term	Description
Salivary Amylase	Enzyme that breaks down starch into sugar in the mouth.
Peristalsis	Rhythmic contraction of muscles to move food forward.
Pepsin	Enzyme that digests proteins in the stomach.
Bile Salts	Help emulsify fats for efficient digestion.
Villi	Finger-like structures in the small intestine that absorb digested food.

🔍 Insights & Higher Order Links:

• The co-ordination between enzymes, muscles, secretions, and pH levels shows a highly regulated biological system.

• Digestive system function reflects the adaptation of anatomy to diet (herbivores vs carnivores).

• A failure in any one part (like lack of bile, pancreatic damage, or loss of villi) can disrupt entire nutrient absorption, leading to malnutrition or illness.

Section 2.2 – Instantaneous Velocity and Speed

Section 2.2 – Instantaneous Velocity and Speed from Class 11 Physics (NCERT Chapter 2: Kinematics):

Section 2.2 – Instantaneous Velocity and Speed

1. Concept of Instantaneous Velocity

• Average velocity gives us an idea of how fast an object moves over a finite time interval.

• However, it does not tell us how fast the object is moving at a particular instant of time during that interval.

To address this, we define:

Instantaneous velocity: The velocity of an object at a specific moment in time.

Mathematically, it is the limit of the average velocity as the time interval becomes infinitesimally small:

$$v = \lim_{\Delta t \to 0} \frac{\Delta x}{\Delta t} = \frac{dx}{dt}$$

This is the derivative of position $x$ with respect to time $t$**—also known as the rate of change of position at that instant.

2. Graphical Representation

• Instantaneous velocity can be visualized using the slope of a position-time graph.

• For example, consider a graph representing the motion of a car:

  • To find velocity at $t = 4$ s:

    • Start by calculating average velocity over small time intervals centered at 4 s (like from 3 s to 5 s, 3.5 s to 4.5 s, etc.).

    • As the interval $\Delta t$ decreases, the secant line between two points approaches a tangent line at the point $t = 4$ s.

    • The slope of this tangent line gives the instantaneous velocity at that instant.

This approach, while useful for visual understanding, is often not practical in real-life calculations because:

• It requires precise graph plotting.

• It involves manually calculating slopes of secant lines repeatedly for smaller intervals.

Position-Time Diagram (Responsive)

Position-Time Graph: x = 0.08t³

Velocity-Time Graph: v = 0.24t²

3. Numerical Illustration

To better understand the limiting process, we can use a numerical example.

Suppose the position of a car is given by:

$$x = 0.08t^3$$

We calculate average velocities using different small values of $\Delta t$, centered at $t = 4.0 \, \text{s}$, by computing:

$$\Delta x = x(t + \frac{\Delta t}{2}) - x(t - \frac{\Delta t}{2})$$ $$\text{Average velocity} = \frac{\Delta x}{\Delta t}$$

Here’s how the process looks:

∆t (s)	t₁ (s)	t₂ (s)	x(t₁) (m)	x(t₂) (m)	∆x (m)	∆x/∆t (m/s)
2.0	3.0	5.0	2.16	10.00	7.84	3.92
1.0	3.5	4.5	3.43	8.49	5.06	5.06
0.5	3.75	4.25	4.22	7.64	3.42	6.84
0.1	3.95	4.05	5.03	6.59	1.56	15.6
0.01	3.995	4.005	5.91	5.99	0.08	8.0

(Values are illustrative for explanation purposes; actual values should follow from the exact expression.)

As $\Delta t \to 0$, the average velocity approaches 3.84 m/s, which is the instantaneous velocity at $t = 4.0 \, \text{s}$.

4. Analytical (Calculus) Method

When the position function $x(t)$ is known, the instantaneous velocity is more conveniently found using differential calculus:

$$x = 0.08 t^3 \Rightarrow \frac{dx}{dt} = 0.24 t^2$$

So at $t = 4.0 \, \text{s}$:

$$v = 0.24 \times 16 = 3.84 \, \text{m/s}$$

This confirms the result obtained from the limiting process.

5. Speed vs. Velocity

• Instantaneous speed is the magnitude of instantaneous velocity.

• It is always positive, whereas velocity can be positive or negative depending on direction.

6. Summary

• Instantaneous velocity gives a more accurate description of how fast an object is moving at a particular instant.

• It is defined as the derivative of position with respect to time.

• It can be calculated:

  • Graphically (as slope of tangent to the position-time curve).

  • Numerically (by reducing ∆t in average velocity).

  • Analytically (using calculus, if position-time relation is known).

• Instantaneous speed is the absolute value of instantaneous velocity.