What are renewable and non-renewable energy sources?

Renewable energy sources are replenished naturally like solar, wind, hydro. Non-renewable sources like fossil fuels are finite and deplete with use.

Give examples of fossil fuels.

Coal, petroleum, and natural gas are examples of fossil fuels used for energy generation.

How is solar energy harnessed?

Solar energy is captured using solar panels that convert sunlight into electricity or heat for practical use.

Energy is the capacity to do work. It exists in many forms — kinetic, potential, thermal, chemical, electrical, nuclear — and is measured in joules (J) or kilowatt-hours (kWh) for electrical energy.

3. What are fossil fuels and how were they formed?

Fossil fuels (coal, oil, natural gas) are formed from ancient plant and animal remains that were buried and subjected to heat and pressure over millions of years, concentrating carbon-rich materials.

5. What is crude oil and what products are obtained by refining it?

Crude oil is a mixture of hydrocarbons extracted from underground. Fractional distillation in refineries produces petrol, diesel, kerosene, lubricating oils, and feedstock for petrochemicals.

6. What is natural gas and how is it used?

Natural gas (primarily methane) is used for cooking, heating, electricity generation, and as feedstock in fertilizers. It burns cleaner than coal or oil but is still a fossil fuel producing CO₂.

8. How does hydroelectric power work and what are its benefits and drawbacks?

Hydroelectricity converts potential energy of stored water in dams into mechanical energy via turbines and then electricity via generators. Benefits: renewable, low emissions, grid-scale storage (pumped storage). Drawbacks: ecological disruption, displacement, siltation, changes to downstream flow.

9. What are the main types of solar energy technology?

Main types: photovoltaic (PV) panels convert sunlight directly to electricity; solar thermal (collectors or concentrated solar power) uses heat for water heating or to drive turbines. Advantages: renewable, low emissions; challenge: intermittency and need for storage.

10. How does a photovoltaic (PV) cell generate electricity?

PV cells are semiconductor (usually silicon) PN-junction devices. Photons generate electron-hole pairs; built-in electric fields separate charges creating current. Cells form modules and arrays; performance depends on irradiance and temperature.

11. How do wind turbines produce electricity?

Wind turbines extract kinetic energy from moving air via rotor blades connected to a shaft and generator (often via gearbox). Siting, wind speed distribution, and capacity factor (actual vs rated output over time) determine productivity.

12. What is biomass and what are its forms as fuel?

Biomass includes wood, crop residues, animal dung, and organic waste. It can be used directly as solid fuel, converted to biogas (methane) via anaerobic digestion, or processed into liquid biofuels (ethanol, biodiesel).

Sources of Energy | Class 10 Science Notes

📘 Introduction

This chapter explains Sources of Energy, covering renewable and non-renewable energy, fossil fuels, solar, wind, and hydro energy. Essential for NEET, SSC, Railway, and Police Bharti exams and Class 10 board preparation.

🔹 Key Concepts

Renewable Energy: Energy sources naturally replenished (solar, wind, hydro)
Non-renewable Energy: Energy sources that are finite like coal, petroleum, natural gas
Fossil Fuels: Coal, petroleum, natural gas — used for electricity & heat
Solar Energy: Captured using solar panels for electricity or heat
Wind Energy: Harnessed using wind turbines
Hydro Energy: Generated from flowing water using dams and turbines

📊 Chapter Summary Table

Concept	Definition / Formula	Use
Renewable Energy	Energy replenished naturally	Sustainable electricity & heat
Non-renewable Energy	Finite energy sources like coal	Limited usage, depleting reserves
Fossil Fuels	Coal, petroleum, natural gas	Electricity, heat, fuel
Solar Energy	Converted sunlight to electricity/heat	Power generation, water heating
Wind Energy	Turbines convert wind to electricity	Green power generation
Hydro Energy	Flowing water produces electricity	Hydroelectric power stations

🧮 Practice Questions

What are the main renewable and non-renewable energy sources? ➡ Show Answer
Renewable: solar, wind, hydro; Non-renewable: coal, petroleum, natural gas.
Explain how solar energy is converted into electricity. ➡ Show Answer
Solar panels convert sunlight into electrical energy using photovoltaic cells.
List the advantages of using wind energy. ➡ Show Answer
Clean, renewable, sustainable, low maintenance, reduces fossil fuel dependency.

Renewable Non-renewable Environmental Impact Storage & Efficiency

NCERT Class 10 — Sources of Energy

13. What is biogas and how is it produced?

14. What is geothermal energy and where is it used?

📘 Introduction

🔹 Key Concepts

📊 Chapter Summary Table

🧮 Practice Questions

1. What is energy?

2. Classify sources of energy with examples.

3. What are fossil fuels and how were they formed?

4. Give advantages and disadvantages of fossil fuels.

5. What is crude oil and what products are obtained by refining it?

6. What is natural gas and how is it used?

7. Name types of coal and their main uses.

8. How does hydroelectric power work and what are its benefits and drawbacks?

9. What are the main types of solar energy technology?

10. How does a photovoltaic (PV) cell generate electricity?

11. How do wind turbines produce electricity?

12. What is biomass and what are its forms as fuel?

13. What is biogas and how is it produced?

14. What is geothermal energy and where is it used?

15. How does tidal energy generate power?

16. What is nuclear energy and how is electricity produced in a nuclear power plant?

17. Difference between renewable and non-renewable energy sources?

18. What is energy conservation and why is it important?

19. What is energy density and how do common fuels compare?

20. What are major energy storage options for electricity grids?

21. What is capacity factor and why does it matter?

22. What is a carbon footprint and how is energy use linked to it?

23. Why consider life-cycle emissions when comparing energy sources?

24. What is energy security and how can it be improved?

25. What role do smart grids play with renewable energy?

26. What is peak load and how is it managed?

27. Give examples of energy-efficiency measures.

28. What are biofuels and what challenges do they present?

29. What is carbon capture and storage (CCS)?

30. What are safer and cleaner cooking options compared to traditional biomass stoves?

31. Quick calculation: How much energy can a 1 kW solar panel produce in a day?

32. What is grid parity?

33. What is distributed generation and its benefits?

34. What is an energy audit and why do one?

35. What are peaking power plants and why are they needed?

36. What is Levelized Cost of Energy (LCOE)?

37. What are hybrid energy systems and where are they useful?

38. What is demand-side management (DSM)?

39. What policy tools encourage renewable deployment?

40. What is meant by 'energy transition'?

41. What role can hydrogen play in future energy systems?

42. How is the intermittency of renewables managed?

43. Summarize environmental impacts of different energy sources.

44. Why is international cooperation important for clean energy deployment?

45. Why is modern energy access important for development?

46. How does the circular economy concept apply to energy technologies?

47. What practical steps can individuals take to reduce energy consumption?

48. What might the future energy mix look like?

49. Quick revision: key units & typical numbers

50. Final high-yield summary: Sources of Energy