Class 10th Science Chapter 14 – Sources of Energy | Important Diagrams, Examples and Applications

Class 10 Science – Chapter 14

Sources of Energy | Important Diagrams, Examples and Applications

महत्वपूर्ण आरेख • उदाहरण • उपयोग • Revision • MCQs • HOTS

⚡ Sources of Energy | Important Diagrams, Examples and Applications

1. Introduction – परिचय

Energy Source: वह प्राकृतिक या मानव-निर्मित स्रोत जिससे उपयोगी ऊर्जा प्राप्त की जाती है, energy source कहलाता है।

Examples: सूर्य, कोयला, पेट्रोलियम, प्राकृतिक गैस, जल, पवन, बायोमास, ज्वार-भाटा, तरंगें, भू-तापीय ऊर्जा तथा नाभिकीय ऊर्जा।

ऊर्जा के स्रोतों को मुख्यतः Renewable और Non-renewable स्रोतों में बाँटा जाता है।

Type	Meaning / अर्थ	Examples / उदाहरण
Renewable Sources	जो प्राकृतिक प्रक्रियाओं द्वारा अपेक्षाकृत लगातार पुनः उपलब्ध होते हैं।	Solar, Wind, Hydro, Tidal, Wave, Geothermal
Non-renewable Sources	सीमित मात्रा में उपलब्ध तथा बनने में बहुत लंबा समय लेते हैं।	Coal, Petroleum, Natural Gas, Uranium

2. Important Diagram – Classification of Energy Sources

Energy Sources Classification / ऊर्जा स्रोतों का वर्गीकरण

3. Solar Energy – सौर ऊर्जा

सूर्य पृथ्वी का सबसे महत्वपूर्ण प्राकृतिक energy source है। Solar energy को heat energy तथा electrical energy में बदला जा सकता है। Solar radiation → Heat / Electricity

Solar Cooker – सौर कुकर

Applications / उपयोग:

• Solar cooker
• Solar water heater
• Solar dryer
• Solar furnace
• Rooftop solar panels
• Solar street lights
• Satellites and spacecraft

4. Solar Cell – सौर सेल

Solar cell एक semiconductor device है जो solar radiation को directly electrical energy में बदलता है। इसे photovoltaic cell भी कहा जाता है।

Solar Cell Working / सौर सेल की कार्यप्रणाली

Solar Cell Applications:
Calculators, satellites, solar street lights, water pumps, rooftop systems, remote communication systems and solar power plants.

5. Wind Energy – पवन ऊर्जा

Moving air possesses kinetic energy. Wind turbine converts the kinetic energy of wind into mechanical energy and then electrical energy.

Wind Turbine / पवन टर्बाइन

Applications:

• Electricity generation
• Water pumping
• Battery charging
• Remote power supply
• Wind farms

6. Hydroelectric Energy – जलविद्युत ऊर्जा

Stored water at a height possesses gravitational potential energy. When water flows downward, this energy is converted into kinetic energy and then mechanical/electrical energy.

Hydroelectric Power Plant

7. Biomass and Biogas – बायोमास और बायोगैस

Biomass: पौधों और जानवरों से प्राप्त जैविक पदार्थ जैसे wood, crop residue, animal waste आदि। Biogas: जैविक waste के anaerobic decomposition से बनने वाली combustible gas। इसमें methane प्रमुख combustible component है।

Biogas Plant / बायोगैस संयंत्र

Biogas Applications: Cooking fuel, small-scale electricity generation, heating and organic manure production.

8. Tidal Energy – ज्वारीय ऊर्जा

Tidal energy समुद्र के जल के periodic rise and fall तथा movement से प्राप्त होती है। इसका मुख्य कारण Moon और Sun का gravitational effect है।

Tidal Barrage Concept

9. Wave Energy – तरंग ऊर्जा

Ocean surface waves mainly obtain their energy from wind. Wave-energy devices convert wave motion into useful mechanical/electrical energy.

Wave Energy Concept

10. Geothermal Energy – भू-तापीय ऊर्जा

Earth के अंदर stored heat energy को geothermal energy कहा जाता है। Hot water और steam का उपयोग electricity generation तथा heating में किया जा सकता है।

Examples / उदाहरण: Hot springs, geothermal power plants, geothermal heating systems.

11. Nuclear Energy – नाभिकीय ऊर्जा

Heavy nuclei such as uranium के controlled fission से बहुत अधिक heat energy release होती है। इस heat का उपयोग steam बनाने और turbine-generator चलाने में किया जाता है।

Nuclear Power Plant – Basic Flow

12. Important Examples – महत्वपूर्ण उदाहरण

Energy Source	Example	Main Energy Conversion
Solar	Solar cooker	Solar radiation → Heat
Solar	Solar cell	Solar radiation → Electricity
Wind	Wind turbine	Wind kinetic energy → Mechanical → Electrical
Hydro	Dam	Gravitational potential → Kinetic → Electrical
Biomass	Biogas plant	Chemical energy → Heat / useful energy
Tidal	Tidal barrage	Water movement → Mechanical → Electrical
Wave	Wave-energy device	Wave motion → Mechanical → Electrical
Geothermal	Geothermal plant	Earth heat → Steam → Electrical
Nuclear	Nuclear power plant	Nuclear → Heat → Mechanical → Electrical

13. Energy Conversion – ऊर्जा रूपांतरण

Energy Source → Conversion Device → Useful Output

Important Examples:

☀ Solar cell:
Solar Energy → Electrical Energy

🌬 Wind turbine:
Wind Kinetic Energy → Mechanical Energy → Electrical Energy

💧 Hydroelectric plant:
Potential Energy of Water → Kinetic Energy → Mechanical Energy → Electrical Energy

☢ Nuclear power plant:
Nuclear Energy → Heat Energy → Mechanical Energy → Electrical Energy

14. Important Applications – प्रमुख उपयोग

Source	Applications
Solar Energy	Cooking, water heating, electricity, drying, satellites, street lighting.
Wind Energy	Electricity generation, water pumping, remote power systems.
Hydroelectric Energy	Large-scale electricity generation and grid supply.
Biogas	Cooking, heating, electricity and manure.
Tidal Energy	Electricity generation at suitable coastal locations.
Wave Energy	Electricity generation in suitable coastal regions.
Geothermal Energy	Electricity generation and heating.
Nuclear Energy	Large-scale electricity generation, research and some specialised applications.

15. Renewable vs Non-renewable – Quick Comparison

Feature	Renewable	Non-renewable
Availability	Naturally replenished on useful time scales.	Limited reserves.
Examples	Solar, wind, hydro, tidal.	Coal, petroleum, natural gas.
Fuel depletion	Generally low during normal use.	Resources can be depleted.
Environmental impact	Often lower operational emissions, but not impact-free.	Many have significant environmental impacts.

16. Numerical Examples – संख्यात्मक उदाहरण

Example 1: A solar device receives 5000 J of solar energy and converts 1000 J into useful energy. Find efficiency.

Efficiency = (Useful Output / Input) × 100
= (1000 / 5000) × 100 = 20%

Answer: 20%

Example 2: A hydroelectric system converts 2 × 10⁶ J of input energy into 5 × 10⁵ J useful electrical energy.

Efficiency = (5 × 10⁵ / 2 × 10⁶) × 100 = 25%

Answer: 25%

Example 3: A solar panel produces 300 W power for 5 hours.

Energy = Power × Time
= 0.3 kW × 5 h
= 1.5 kWh

Answer: 1.5 kWh

17. Important MCQs – 30 Questions

Q1. Which is a renewable source of energy?

A) Coal

B) Petroleum

C) Solar energy

D) Natural gas

Answer: C – Solar energy is continuously supplied by the Sun.

Q2. A solar cell converts:

A) Electrical energy into heat

B) Solar energy directly into electrical energy

C) Electrical energy into light

D) Heat into chemical energy

Answer: B

Q3. The main source of energy for wind is:

A) Sun

B) Moon

C) Earth’s core

D) Nuclear fuel

Answer: A

Q4. Which device converts wind energy into electrical energy?

A) Solar cooker

B) Wind turbine

C) Transformer

D) Solar cell

Answer: B

Q5. In a hydroelectric plant, the initial useful stored energy of water is mainly:

A) Chemical

B) Nuclear

C) Gravitational potential

D) Magnetic

Answer: C

Q6. Which gas is an important combustible component of biogas?

A) Oxygen

B) Methane

C) Nitrogen

D) Hydrogen chloride

Answer: B

Q7. Tidal energy is mainly associated with:

A) Ocean tides

B) Forest fires

C) Underground coal

D) Lightning

Answer: A

Q8. Wave energy is mainly associated with:

A) Ocean surface waves

B) Groundwater

C) Coal mines

D) Nuclear fission

Answer: A

Q9. Geothermal energy comes mainly from:

A) Moonlight

B) Earth’s internal heat

C) Wind

D) Coal

Answer: B

Q10. Nuclear power plants commonly obtain energy from:

A) Nuclear fission

B) Photosynthesis

C) Evaporation only

D) Tidal heating

Answer: A

Q11. The main function of a generator in a power plant is to:

A) Store fuel

B) Convert mechanical energy into electrical energy

C) Convert electricity into coal

D) Absorb sunlight

Answer: B

Q12. Which device is specifically used for cooking using solar radiation?

A) Solar cooker

B) Wind turbine

C) Generator

D) Turbine

Answer: A

Q13. Which energy source is associated with anaerobic decomposition?

A) Solar

B) Biogas

C) Wind

D) Tidal

Answer: B

Q14. Which source is non-renewable?

A) Wind

B) Solar

C) Coal

D) Tidal

Answer: C

Q15. Which energy source is highly dependent on availability of sunlight?

A) Solar

B) Nuclear

C) Geothermal

D) Tidal

Answer: A

Q16. A wind turbine primarily receives:

A) Chemical energy

B) Kinetic energy of moving air

C) Nuclear energy

D) Magnetic energy

Answer: B

Q17. Which source can be considered predictable compared with wind and solar at suitable locations?

A) Tidal

B) Biomass

C) Coal

D) Petroleum

Answer: A

Q18. A solar panel is generally made from:

A) Many interconnected solar cells

B) Only one wire

C) Only a battery

D) A turbine

Answer: A

Q19. Which energy conversion occurs in a solar cell?

A) Solar → Electrical

B) Electrical → Solar

C) Mechanical → Nuclear

D) Chemical → Nuclear

Answer: A

Q20. Which is a major application of geothermal energy?

A) Electricity generation

B) Coal formation

C) Petroleum refining only

D) Photosynthesis

Answer: A

Q21. Which energy source uses water stored at a height?

A) Hydroelectric

B) Wind

C) Solar

D) Nuclear

Answer: A

Q22. The energy stored in biomass is primarily:

A) Chemical energy

B) Magnetic energy

C) Nuclear energy

D) Gravitational energy

Answer: A

Q23. Which is an example of direct conversion of solar radiation into electricity?

A) Solar cell

B) Solar cooker

C) Solar water heater

D) Solar dryer

Answer: A

Q24. Which source is obtained from ocean surface motion?

A) Wave energy

B) Geothermal

C) Biomass

D) Nuclear

Answer: A

Q25. In nuclear power generation, the reactor mainly provides:

A) Heat

B) Wind

C) Sunlight

D) Tidal water

Answer: A

Q26. Which source involves gravitational effects of Moon and Sun on ocean water?

A) Tidal energy

B) Solar cell

C) Geothermal energy

D) Biomass

Answer: A

Q27. Which device converts mechanical energy into electrical energy?

A) Generator

B) Solar cooker

C) Battery only

D) Insulator

Answer: A

Q28. Which source can produce energy without combustion of a fuel during normal operation?

A) Solar PV

B) Coal

C) Petrol

D) Diesel

Answer: A

Q29. Which is an important limitation of solar energy?

A) It is dependent on sunlight availability

B) It is non-renewable

C) It always produces smoke

D) It requires coal

Answer: A

Q30. Which statement is correct?

A) Renewable energy sources have absolutely zero environmental impact

B) Every energy source has some advantages and limitations

C) Coal is renewable

D) Solar cells burn fuel to produce electricity

Answer: B

18. Subjective Questions – 30 Questions with Answers

2 Marks Q1. What is a renewable source of energy?

A renewable source is naturally replenished on a useful time scale. Examples include solar and wind energy.

2 Marks Q2. What is a solar cell?

A solar cell is a semiconductor device that converts solar radiation directly into electrical energy.

2 Marks Q3. Name two applications of solar energy.

Solar cooking and electricity generation using solar cells.

2 Marks Q4. What is biogas?

Biogas is a combustible gas mixture produced by anaerobic decomposition of organic matter. Methane is its major combustible component.

2 Marks Q5. What is tidal energy?

Tidal energy is energy obtained from the periodic movement and rise and fall of ocean water.

2 Marks Q6. Name two non-renewable sources.

Coal and petroleum.

3 Marks Q7. Explain the working principle of a solar cell.

Solar radiation falls on a semiconductor junction. It creates charge carriers and produces a potential difference. When an external circuit is connected, electric current flows.

3 Marks Q8. Explain the energy conversion in a hydroelectric power plant.

Water stored at height has gravitational potential energy. Falling water gains kinetic energy and rotates turbines. The generator converts mechanical energy into electrical energy.

3 Marks Q9. Write three applications of wind energy.

Electricity generation, water pumping and battery/remote power supply.

3 Marks Q10. Explain the basic working of a biogas plant.

Organic waste is fed into a digester. Anaerobic microorganisms decompose the waste and produce biogas. The remaining slurry can be used as manure.

3 Marks Q11. Why is solar energy considered renewable?

The Sun continuously supplies solar radiation on human time scales, so solar energy is naturally replenished.

3 Marks Q12. Differentiate between wave and tidal energy.

Wave energy uses ocean surface-wave motion, mainly generated by wind. Tidal energy uses periodic ocean-water movement associated mainly with gravitational effects of the Moon and Sun.

4 Marks Q13. Explain the construction and working of a solar cooker.

A box-type solar cooker has an insulated box, blackened inner surface, transparent glass cover and often a reflector. Black surfaces absorb radiation. The glass cover helps trap heat, raising the temperature inside and cooking food.

4 Marks Q14. Explain wind energy conversion.

Moving air rotates turbine blades. The turbine transfers mechanical energy to a generator. The generator converts mechanical energy into electrical energy.

4 Marks Q15. Explain geothermal energy with applications.

Geothermal energy is obtained from Earth’s internal heat. Underground hot water or steam can be brought to the surface and used for electricity generation or heating.

4 Marks Q16. Explain the main components of a nuclear power plant.

The major components include a nuclear reactor, heat/steam generation system, turbine, generator and cooling system. The reactor supplies heat, steam drives the turbine and the generator produces electricity.

4 Marks Q17. Give four applications of solar cells.

Solar cells are used in calculators, satellites, street lights and rooftop solar systems.

4 Marks Q18. Explain two advantages and two limitations of wind energy.

Advantages: renewable and produces electricity without fuel combustion during normal operation. Limitations: output varies with wind availability and suitable sites are required.

5 Marks Q19. Compare renewable and non-renewable sources of energy.

Renewable sources are naturally replenished, such as solar, wind and tidal energy. Non-renewable sources have limited reserves, such as coal and petroleum. Renewable sources can reduce dependence on finite fuels, although they also have environmental and land-use considerations.

5 Marks Q20. Explain hydroelectric power generation with a labelled diagram.

Water is stored behind a dam. Its potential energy changes to kinetic energy when released. Flowing water rotates a turbine connected to a generator, which produces electricity.

5 Marks Q21. Explain solar cell construction, working and applications.

A solar cell uses semiconductor material forming a p-n junction with electrical contacts. Incident light generates charge carriers, and the internal electric field helps separate them. Current flows through an external circuit. Solar cells are used in satellites, calculators, rooftop systems and street lights.

5 Marks Q22. Explain the working of a biogas plant.

Organic material is mixed with water and introduced into an anaerobic digester. Microorganisms decompose it without oxygen, producing biogas. The gas is collected and used as fuel, while the residual slurry can be used as manure.

5 Marks Q23. Explain tidal energy and its applications.

Tidal energy arises from periodic ocean-water movement. Barrages or tidal-stream systems can capture this movement and drive turbines. Its main application is electricity generation at suitable coastal locations.

6 Marks Q24. Describe important renewable energy sources and their applications.

Solar energy is used for heating and electricity. Wind energy is used in turbines. Hydroelectric energy uses falling water. Tidal and wave energy use ocean movement. Geothermal energy uses Earth’s internal heat. Biomass can provide fuel and biogas. Their applications range from domestic systems to large-scale electricity generation.

6 Marks Q25. Explain energy conversion in solar, wind and hydroelectric systems.

Solar cell: solar radiation → electrical energy.
Wind turbine: wind kinetic energy → mechanical energy → electrical energy.
Hydroelectric plant: gravitational potential energy → kinetic energy → mechanical energy → electrical energy.

6 Marks Q26. Explain nuclear energy generation.

Controlled nuclear fission releases heat in a reactor. Heat produces steam. Steam rotates a turbine, and the turbine drives a generator. The generator converts mechanical energy into electrical energy. Cooling and safety systems are essential components of the plant.

6 Marks Q27. Discuss applications and limitations of solar energy.

Applications include solar cookers, water heaters, dryers, photovoltaic systems, street lights and satellites. Limitations include dependence on sunlight, reduced output under clouds/night, need for suitable installation area and possible need for storage or backup.

6 Marks Q28. Explain why no energy source can be considered completely impact-free.

Energy technologies require materials, land, construction and maintenance. Solar and wind can have land and ecological effects; hydro can alter river systems; biomass can cause emissions if poorly managed; nuclear produces radioactive waste; fossil fuels cause major air pollution and greenhouse-gas emissions.

6 Marks Q29. Explain the role of energy conservation along with renewable energy.

Energy conservation reduces unnecessary energy consumption. Efficient appliances, public transport, LED lighting and reduced wastage lower demand. Renewable energy then helps meet the remaining demand with reduced dependence on finite fuels.

6 Marks Q30. Draw and explain any three important energy-conversion diagrams.

Students may draw:
1. Solar cell: Solar → Electrical.
2. Wind turbine: Wind → Turbine → Generator → Electricity.
3. Hydroelectric plant: Water at height → Turbine → Generator → Electricity.

19. Assertion–Reason Questions

Q1. Assertion: Solar energy is renewable.
Reason: The Sun continuously supplies energy on human time scales.

Answer: Both Assertion and Reason are true, and Reason correctly explains Assertion.

Q2. Assertion: A solar cell directly produces electrical energy from sunlight.
Reason: A solar cell works using photovoltaic conversion.

Answer: Both statements are true, and the Reason correctly explains the Assertion.

Q3. Assertion: Hydroelectric plants use water stored at a height.
Reason: Stored water possesses gravitational potential energy.

Answer: Both are true, and the Reason correctly explains the Assertion.

Q4. Assertion: Coal is a renewable energy source.
Reason: Coal is formed very rapidly.

Answer: Both Assertion and Reason are false.

Q5. Assertion: Wind turbines require moving air.
Reason: Wind possesses kinetic energy.

Answer: Both statements are true, and the Reason correctly explains the Assertion.

20. HOTS – Higher Order Thinking Questions

Q1. A village receives strong sunlight throughout most of the year but has unreliable grid electricity. Which energy technology could be particularly useful and why?

Solar photovoltaic systems can generate electricity locally from sunlight. Battery storage or another backup may be added when electricity is required after sunset or during low-sunlight periods.

Q2. Why may a coastal region consider both tidal and wave energy, but not necessarily at every coastal location?

Both depend on suitable marine conditions. Tidal systems require sufficient tidal range or current, while wave systems require suitable wave climate. Installation, cost, ecology and engineering conditions also determine suitability.

Q3. Why is a solar cell different from a solar cooker even though both use sunlight?

A solar cell converts solar radiation directly into electrical energy, whereas a solar cooker mainly converts solar radiation into heat for cooking.

Q4. Why can a renewable source still have environmental consequences?

Construction and operation may require land, materials, water or infrastructure and may affect habitats. Renewable means naturally replenished, not completely impact-free.

Q5. Why is energy conversion efficiency important?

Higher efficiency means a greater fraction of input energy becomes useful output, reducing energy wastage and often reducing the amount of input resource needed for the same useful output.

21. Golden Points – परीक्षा के लिए महत्वपूर्ण बिंदु

✔ Solar cell → Solar energy to electrical energy.

✔ Solar cooker → Solar energy to heat energy.

✔ Wind turbine → Wind energy to mechanical/electrical energy.

✔ Hydroelectric plant → Potential energy of water to electrical energy.

✔ Biogas → Anaerobic decomposition; methane is major combustible component.

✔ Tidal energy → Periodic ocean-water movement.

✔ Wave energy → Ocean surface-wave motion.

✔ Geothermal → Earth’s internal heat.

✔ Nuclear power → Controlled nuclear fission → heat → electricity.

✔ Renewable does NOT mean zero environmental impact.

22. One-Minute Revision

Solar: Sun → Heat/Electricity

Wind: Moving air → Turbine → Generator

Hydro: Height of water → Turbine → Generator

Biogas: Organic waste → Anaerobic digestion → Biogas

Tidal: Ocean tides → Turbine → Electricity

Wave: Ocean waves → Device → Electricity

Geothermal: Earth heat → Steam → Electricity

Nuclear: Fission → Heat → Steam → Turbine → Generator

23. Concept Map

24. Final Summary – अंतिम सारांश

Sources of energy हमारे जीवन, उद्योग, परिवहन और electricity generation के लिए अत्यंत महत्वपूर्ण हैं। Solar, wind, hydro, biomass, tidal, wave और geothermal जैसे sources renewable हैं, जबकि coal, petroleum, natural gas तथा nuclear fuel सीमित resources पर आधारित हैं।

Exam में विशेष रूप से solar cooker, solar cell, wind turbine, hydroelectric power plant, biogas plant, tidal energy, wave energy, geothermal energy और nuclear power plant के diagrams, energy conversions, examples और applications याद रखें।

सबसे महत्वपूर्ण बात यह है कि किसी energy source का मूल्यांकन केवल उसकी availability से नहीं, बल्कि उसकी efficiency, reliability, cost, resource availability और environmental consequences को ध्यान में रखकर किया जाता है।

Class 10 CBSE Science – Sources of Energy
Important Diagrams • Examples • Applications • MCQs • HOTS • Revision

⚡ Learn the concept • Understand the conversion • Draw the diagram • Apply the knowledge