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Energy

NCERT Class 5 · EVS Based on NCERT Class 5 EVS textbook · Free CBSE study kit

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Chapter Notes

Overview
This chapter introduces the concept of energy by connecting it to everyday experiences. It explains that energy is what makes things move, light up, produce sound, and change temperature. Students explore different sources of energy — food for living beings, fuels like petrol and cooking gas, electricity, and natural sources like the Sun, wind, and water. The big idea is that energy is everywhere and we must use it wisely, choosing clean sources to protect our environment.
Key Concepts (13)
Energy
Energy is what makes things move, light up, produce sound, do work and change temperature.
e.g. When we release air from a balloon, the air rushes out and pushes the balloon forward — this movement is caused by energy.
Sound energy
Sound energy is produced when objects vibrate, creating sound.
e.g. Plucking rubber bands stretched over a cardboard box makes them vibrate and produce sound — this is sound energy.
Heat energy
Heat energy is the energy that makes things warmer.
e.g. Water kept in sunlight becomes warmer because the Sun gives heat energy.
Source of energy
A source of energy is anything that provides energy to do work.
e.g. Food is a source of energy for humans and animals; petrol is a source of energy for vehicles.
Fuel
A fuel is a substance that is burned to produce heat or energy.
e.g. Cooking gas, petrol, diesel, wood, and coal are fuels used for cooking and running vehicles.
Electricity
Electricity is a form of energy that can be used for movement, producing sound, light, and heat.
e.g. A fan uses electricity to move its blades and blow air.
Clean energy
Clean energy is electricity generated using natural sources like the Sun, wind, or water that does not pollute the planet with smoke or waste.
e.g. Solar panels capture sunlight and turn it into electricity without producing smoke.
Energy efficiency
Energy efficiency means using less energy to do the same work, helping save resources and reduce waste.
e.g. Using LED bulbs instead of incandescent bulbs gives the same amount of light but uses less electricity.
Stored energy
Stored energy is energy that is saved for future use.
e.g. Batteries in a torch or toy contain stored energy; our body stores energy from food so we can run even if we skip a meal.
Vibration
Vibration is a rapid back-and-forth movement that produces sound.
e.g. When you pluck a rubber band, it vibrates and creates sound.
Solar energy
Solar energy is energy from the Sun that can be used to produce heat and electricity.
e.g. The Bhadla Solar Park in Rajasthan uses solar panels to capture sunlight and generate electricity.
Wind energy
Wind energy is energy from moving air that can be used to do work or generate electricity.
e.g. A pinwheel rotates when held in the wind; windmills spin with the wind to make electricity.
Hydro energy / Water energy
Hydro energy is energy from flowing or falling water that can be used to do work or generate electricity.
e.g. In hilly areas, watermills called gharaats use flowing water to grind grains.
How It Works
How a balloon rocket works (movement energy from air)
  1. Blow air into a balloon and hold it tightly.
  2. Attach the balloon to a straw with tape.
  3. Pass a string through the straw and hold the ends.
  4. Release the mouth of the balloon.
  5. Air rushes out of the balloon, pushing it forward along the string.
💡 Students often think the balloon moves because the air is 'pushing' from behind — actually, the escaping air exerts a force in the opposite direction (Newton's third law), propelling the balloon forward.
How a rubber band guitar produces sound (sound energy from vibration)
  1. Make a hole on the top of a cardboard box.
  2. Stretch rubber bands around the box and across the hole.
  3. Place a ruler or pencil under the bands at one end to raise them.
  4. Pluck the bands.
  5. The bands vibrate and produce sound.
💡 Thinner rubber bands produce higher-pitched sounds; thicker bands produce lower-pitched sounds. Students often forget that the vibration is the cause of the sound.
How sunlight heats water (heat energy from the Sun)
  1. Fill two cups with water.
  2. Place one cup in direct sunlight and the other in the shade.
  3. Wait for 15–20 minutes.
  4. Touch the water in both cups.
  5. The water in sunlight is warmer because the Sun gives heat energy.
💡 Students may think the cup in sunlight gets warmer only because of the air temperature — the key is that sunlight directly transfers heat energy to the water.
How a diya burns (fuel and combustion)
  1. Place two diyas on a flat surface.
  2. In Diya 1, place a cotton wick without any oil.
  3. In Diya 2, place a cotton wick and pour some oil around it.
  4. Light both wicks under adult supervision.
  5. Diya 2 burns longer because the oil acts as fuel; Diya 1 goes out quickly as the wick alone burns out.
💡 The wick alone is not the fuel — the oil is the fuel. The wick draws the oil up and helps it burn. Students often think the wick itself is the fuel.
How a pinwheel works (wind energy to movement)
  1. Take a square piece of paper.
  2. Draw its two diagonals to get four equal parts.
  3. Cut halfway along each of the four lines.
  4. Fold each corner and pin it to a stick.
  5. Hold the pinwheel in the wind or run with it.
  6. The wind pushes the blades, making the pinwheel rotate.
💡 The pinwheel rotates because moving air (wind) exerts force on the blades. Students may think it works only in strong wind — even a gentle breeze or running can make it spin.
How a magnifying glass focuses sunlight (heat energy from concentrated sunlight)
  1. Take a piece of paper and a magnifying glass.
  2. Place the paper in direct sunlight.
  3. Use the magnifying glass to focus the sunlight onto the paper.
  4. The concentrated sunlight heats the paper and can burn it.
💡 This activity must be done under adult supervision. Students often forget that the magnifying glass does not create heat — it concentrates the Sun's heat energy onto a small spot.
How a water wheel works (hydro energy to movement)
  1. Take an empty paper cup and five spoons.
  2. Make five holes around the cup and insert the spoons.
  3. Insert a pencil or straw through the bottom of the cup.
  4. Balance the wheel on a container.
  5. Pour water onto the wheel.
  6. The flowing water pushes the spoons, making the wheel spin.
💡 The water must hit the spoons at an angle to make the wheel turn. Students may think any amount of water will work — the force of flowing water is what causes movement.
Exam Traps — Don't Make These Mistakes
⚠ Confusing fuel with the wick in a diya
✗ The wick is the fuel because it burns.
→ The wick does burn, but it is not the main source of energy. The oil is the fuel; the wick only draws the oil up by capillary action and helps it burn steadily.
✓ In a diya, the oil is the fuel. The wick absorbs the oil and helps it burn, but the oil provides the energy for the flame.
⚠ Thinking electricity is the only source of energy
✗ Energy only comes from electricity.
→ Electricity is one form of energy, but energy comes from many sources: food, fuels (petrol, cooking gas), the Sun, wind, water, and even our own bodies.
✓ Energy comes from various sources including food, fuels, electricity, sunlight, wind, and flowing water.
⚠ Mistaking 'clean energy' for 'no energy used'
✗ Clean energy means we do not use any energy.
→ Clean energy still uses energy — it just comes from natural sources that do not pollute. For example, solar panels use sunlight to generate electricity without smoke.
✓ Clean energy is energy from natural sources like the Sun, wind, and water that does not produce smoke or harmful waste.
⚠ Thinking the Sun only gives light, not heat
✗ The Sun only gives us light.
→ The Sun gives both light and heat energy. The activity with cups of water in sunlight and shade proves that sunlight provides heat energy.
✓ The Sun gives us both light and heat energy. For example, water kept in sunlight becomes warmer because of the Sun's heat energy.
⚠ Confusing 'energy efficiency' with 'saving energy by not using it'
✗ Energy efficiency means we should not use energy at all.
→ Energy efficiency means using less energy to do the same work, not avoiding energy use. For example, an LED bulb gives the same light as a regular bulb but uses less electricity.
✓ Energy efficiency means using less energy to perform the same task, such as using an LED bulb instead of a regular bulb to save electricity.
Compare & Contrast
Source of energy for what?
Fuel (like petrol, diesel, cooking gas)
Food
Fuel provides energy for vehicles and cooking appliances; food provides energy for living beings (humans and animals).
Effect on the environment
Clean energy (solar, wind, hydro)
Energy from burning coal
Clean energy does not produce smoke or harmful waste and does not pollute the planet; burning coal produces smoke and harmful gases that pollute the air and harm health.
Exam Focus
Marks pattern: 2 MCQs (1 mark each), 1 Short Answer (3 marks), 1 Long Answer (5 marks) — typically covering definitions, sources, and one activity explanation.
Most asked: Definition and examples of energy · Sources of energy (food, fuel, electricity, Sun, wind, water) · Clean energy and its importance · Safe use of electricity · Activities demonstrating energy (balloon rocket, rubber band guitar, pinwheel, water wheel)
Don't skip: Explain what energy is and give two examples from everyday life.; Differentiate between clean energy and energy from burning coal.; Describe one activity that shows how wind or water can be a source of energy.
One-Line Revision (read aloud before the exam)
  1. Energy is what makes things move, light up, produce sound, do work, and change temperature.
  2. Food is a source of energy for all living things, including humans and animals.
  3. Fuels like petrol, diesel, cooking gas, wood, and coal provide energy for vehicles and cooking.
  4. Electricity can be used for movement, light, sound, heat, and cooling.
  5. Clean energy comes from natural sources like the Sun, wind, and water and does not pollute.
  6. The Sun gives both light and heat energy.
  7. Sound energy is produced when objects vibrate.
  8. Energy efficiency means using less energy to do the same work, like using an LED bulb.
  9. Stored energy is found in batteries and in our bodies from food.
  10. Burning wood or coal creates smoke and pollution, so we must use them carefully.
  11. Solar panels capture sunlight and turn it into electricity.
  12. Windmills use wind energy to generate electricity.
  13. Flowing water in rivers or watermills can be used to generate energy.
  14. Do not touch electrical wires or put objects into sockets — electricity can be dangerous.
  15. The Bhadla Solar Park in Rajasthan is one of the largest solar power plants in the world.
  16. Cochin International Airport is the world's first airport entirely powered by solar energy.

MCQs — 10 Questions with Answers

Q1. What is energy?

  • A. Something that makes things move, light up, and do work ✓
  • B. Only electricity we use at home
  • C. Something that costs money
  • D. Only the Sun's heat

Answer: A — Energy is the force that makes things move, produce light, make sounds, and change temperature in many ways.

Q2. In the balloon activity, when you release the balloon, what makes it move?

  • A. The shape of the balloon
  • B. Air rushing out of the balloon ✓
  • C. Your hand pushing it
  • D. The color of the balloon

Answer: B — The moving air pushing out of the balloon is the energy that makes the balloon move forward.

Q3. What is the main source of energy for all living things?

  • A. Water
  • B. Air
  • C. Food ✓
  • D. Soil

Answer: C — Food provides energy to humans and animals, allowing them to move, grow, and work every day.

Q4. In the rubber band guitar activity, what happens when you pluck the rubber bands?

  • A. They become thicker
  • B. They vibrate and produce sound ✓
  • C. They turn into strings
  • D. They stop moving

Answer: B — When rubber bands vibrate by plucking, they make sound energy, which we hear as musical sounds.

Q5. Fill in the blank: Water in sunlight becomes warmer because the Sun gives us _____ energy.

  • A. sound
  • B. movement
  • C. heat ✓
  • D. light only

Answer: C — The Sun provides heat energy that warms the water, as shown in the sun-powered water warmer activity.

Q6. What fuels do people use to cook food at home? (Choose the correct one)

  • A. Only petrol
  • B. Cooking gas, wood, or coal ✓
  • C. Only electricity
  • D. Only water

Answer: B — Cooking gas, wood, and coal are all fuels that provide heat energy to cook food in different homes across India.

Q7. Why do you feel more active after eating breakfast?

  • A. Because you sit down to eat
  • B. Because food gives your body energy ✓
  • C. Because breakfast is tasty
  • D. Because it is morning time

Answer: B — Food is a source of energy, so when we eat breakfast, we get energy to move, run, and do activities.

Q8. In some cold regions like Himachal Pradesh, how do people stay warm without using extra firewood?

  • A. By using electric heaters
  • B. By keeping cattle on the ground floor whose body heat warms the rooms ✓
  • C. By closing all windows and doors
  • D. By eating more hot food

Answer: B — The body heat from cattle on the ground floor is a natural energy source that warms the rooms above where the family lives.

Q9. Which of these is NOT a source of energy mentioned in the chapter?

  • A. Food
  • B. Sun
  • C. Cooking gas
  • D. Plastic bags ✓

Answer: D — Plastic bags are materials, not sources of energy, while food, sun, and cooking gas all provide energy to make things work.

Q10. What do vehicles like cars and scooters need to keep running on the road?

  • A. Sunlight
  • B. Food
  • C. Petrol and diesel fuel ✓
  • D. Water

Answer: C — Petrol and diesel are fuel sources that provide the energy needed to make vehicles move and run on roads.

Flashcards

What is energy?

Energy is what makes things move, light up, produce sound, do work, and change temperature.

Name one source of energy for living things.

Food is a source of energy for all living things like humans and animals.

What happens when you pluck a rubber band?

The rubber band vibrates and produces sound energy.

How does a balloon move after you release it?

The air rushing out of the balloon pushes it forward, showing movement energy from moving air.

What fuel do we use to cook food at home?

Cooking gas, wood, or coal are fuels we use to cook food at home.

What makes water warm in the sun activity?

The Sun's heat energy warms the water when it is kept in sunlight.

Why do we feel tired when we are hungry?

Food gives us energy, so when we do not eat, we lack energy and feel tired.

What do cars and scooters need to keep running?

Petrol and diesel are fuels that provide energy for vehicles to run.

Name one activity in your kitchen that uses energy.

Food is being cooked on the stove using heat energy from gas or fuel.

How do animals get energy to move and find food?

Animals get energy from the food they eat, just like humans do.

Important Board Questions

What is energy? Give one example from your kitchen. [1 mark]

Energy = what makes things move, light up, or get warm. Example: gas stove cooking food uses heat energy.

Describe the balloon activity and explain what makes the balloon move. What kind of energy is this? [2 marks]

When you blow air into a balloon and release it, moving air pushes it forward. This is movement energy from moving air.

Name three different sources of energy we use every day at home and in our community. Explain how each one helps us. [3 marks]

Sources: food (gives us energy to move), cooking gas (heats food), sun (warms rooms, free energy). Explain what each source helps us do or make.

How does the sun-powered water warmer activity show energy at work? Describe the activity step by step and explain what you observed. Why does the water in sunlight become warmer than the water in shade? [5 marks]

Steps: fill two cups with water, place one in sun and one in shade, wait 15-20 minutes, touch both cups. The sun's heat energy warms the water in sunlight. Heat energy from the sun is transferred to the water, raising its temperature.

True or False: Burning wood and coal to cook food is the same as using sunlight to warm water. Give a reason for your answer. [2 marks]

False. Burning wood/coal makes smoke (bad for air), but sun energy is clean and free. Write why one is better than the other.

Assertion-Reason Questions for Energy

Q1. Assertion (A):

Energy is needed for a flying bird to move through the air.

Reason (R):

Birds get energy from the food they eat, which helps them fly, run, and move.

Answer: A — Both A and R are true, and R is the correct explanation of A — Both the assertion and reason are true. The reason correctly explains why birds can move — they get energy from food. This is directly stated in the chapter.

Q2. Assertion (A):

The water in the sunlight became warmer in the Sun-powered Water Warmer activity.

Reason (R):

The cup in shade was placed in darkness, so water became cold.

Answer: B — Both A and R are true, but R is NOT the correct explanation of A — The assertion is true — the water in sunlight did become warmer. However, the reason is not the correct explanation. The reason should be that the Sun gives heat energy, not that shade makes water cold. Both are true, but the reason doesn't explain the assertion.

Q3. Assertion (A):

Burning wood creates smoke in the kitchen.

Reason (R):

Smoke is created because wood is a solid material.

Answer: C — A is true but R is false — The assertion is true — the chapter states that burning wood creates smoke. However, the reason is false. Smoke is created because of the byproducts of burning, not simply because wood is solid. Many solids do not create smoke when heated.

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Case-Based Questions (CBQ) for Energy

Case Study:

Rina's family has a small kitchen at home. Every morning, her mother prepares breakfast. She uses cooking gas to heat water for tea and to cook the food. Rina notices that the gas flame produces heat and light. She also observes that when the water heats up, steam rises from the pot. Today, Rina wondered: 'How does the gas make all these things happen?'

Q1. What is the fuel used in Rina's kitchen for cooking?

  • A. Petrol
  • B. Cooking gas ✓
  • C. Firewood
  • D. Electricity only

Answer: B

Q2. Which forms of energy does the gas flame produce according to the passage?

  • A. Only heat
  • B. Only light
  • C. Heat and light ✓
  • D. Sound only

Answer: C

Q3. Why does steam rise from the pot when water heats up?

  • A. Because the pot is too small
  • B. Because heat energy from the gas changes water into steam ✓
  • C. Because the kitchen is hot
  • D. Because the lid is open

Answer: B

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