Class 10 Science Chapter 14:
Sources of Energy
Summary:
This chapter explores the various sources of energy, both conventional and non-conventional. It discusses the advantages and disadvantages of different energy sources and highlights the importance of conserving energy for a sustainable future.
Key Concepts:
∆ Characteristics of a Good Source of Energy:
i) High calorific value (produces a large amount of energy per unit mass or volume).
ii) Economical and easily accessible.
iii) Easy to store and transport.
iv) Environmentally friendly (minimal pollution).
∆ Conventional Sources of Energy:
i) Fossil Fuels: Coal, petroleum, and natural gas are non-renewable sources formed from the remains of ancient plants and animals. They are major sources of energy but contribute to pollution and environmental degradation.
ii) Thermal Power Plants: These plants burn fossil fuels to generate electricity, releasing harmful gases into the atmosphere.
iii) Hydropower: Utilizes the kinetic energy of flowing water to generate electricity. It is a renewable source but can have significant environmental impacts.
∆ Non-Conventional Sources of Energy:
i) Solar Energy: Energy from the Sun, harnessed using solar cells or solar panels. It is a clean and renewable source.
ii) Wind Energy: Kinetic energy of wind is converted into electricity using wind turbines.
iii) Biogas: Produced from the decomposition of organic matter like animal waste and crop residues.
iv) Geothermal Energy: Utilizes the heat from the Earth's interior to generate electricity.
v) Nuclear Energy: Obtained from nuclear fission or fusion reactions. It is a powerful source but raises concerns about safety and waste disposal.
vi) Tidal and Wave Energy: Derived from ocean movements. They are renewable but have technological and environmental challenges.
∆ Environmental Consequences:
A) Energy production and consumption can lead to environmental degradation.
B) Burning fossil fuels releases greenhouse gases, contributing to global warming.
C) Nuclear energy poses challenges in managing radioactive waste.
D) Sustainable energy practices are essential to minimize environmental impact.
∆ Energy Conservation:
Reducing energy consumption through efficient use of appliances, switching off lights and fans when not in use, and using public transport.
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Most important questions and answers from Chapter 14, "Sources of Energy," in Class 10 Science:
Q. Define a good source of energy.
Answer:
A good source of energy should:
A) Have a high calorific value (produce more energy per unit).
B) Be cost-effective and easily accessible.
C) Be easy to store and transport.
D) Cause minimal pollution or environmental harm.
E) Be renewable or sustainable for long-term use.
Q. What are the different types of energy sources?
Answer : i) Conventional Sources: Fossil fuels (coal, petroleum, natural gas), hydropower, thermal power plants.
ii) Non-Conventional Sources: Solar energy, wind energy, biogas, geothermal energy, nuclear energy.
Q) What are the advantages and disadvantages of fossil fuels?
Answer :
Advantages: Readily available, high energy density, relatively inexpensive.
Disadvantages: Non-renewable, cause pollution, contribute to climate change.
Q. What are the environmental consequences of using fossil fuels?
Answer:
a) Release of carbon dioxide contributes to global warming.
b) Emission of sulfur and nitrogen oxides leads to acid rain, affecting soil and water bodies.
c) Extraction processes can result in habitat destruction and oil spills.
Q. Why is there a need to switch to alternative energy sources?
Answer:
a) Fossil fuels are depleting rapidly.
b) Conventional energy sources cause significant environmental damage.
c) Alternative sources are renewable and sustainable.
d) They reduce greenhouse gas emissions and minimize global warming.
Q. What are the advantages of wind energy?
Answer:
i) It is a renewable and non-polluting source of energy.
ii) Operational costs are low after installation.
iii) Does not emit greenhouse gases or other pollutants.
iv) Reduces dependency on fossil fuels.
Q. What are the limitations of wind energy?
Answer:
Requires consistent and strong wind speeds. High initial setup cost for wind turbines and infrastructure. Wind farms require large areas of land. Can affect the local wildlife, particularly birds and bats.
Q. How is solar energy harnessed?
Answer: Solar cells convert sunlight directly into electricity through the photovoltaic effect. Solar panels collect and concentrate sunlight to heat water or generate electricity.
Q. What are the advantages and disadvantages of solar energy?
Answer:
Advantages:
i) Solar energy is abundant, renewable, and pollution-free.
ii) It reduces dependency on fossil fuels.
iii) It can be used in remote areas.
Disadvantages:
i) Solar panels have a high initial cost.
ii) Efficiency depends on sunlight availability, making it location-specific.
iii) Energy storage systems, like batteries, increase costs.
8. Explain how hydropower plants generate electricity.
Answer: Water stored in a dam is released, flowing through turbines.The kinetic energy of the flowing water rotates the turbines.This rotation is converted into electrical energy using a generator.
Q. What are the environmental consequences of hydropower plants?
Answer:
a) Large areas of land and forests are submerged, affecting biodiversity.
b) Displacement of local communities.
c) Alteration of river ecosystems and natural water flow.
d) Potential for methane emissions from decomposing vegetation in reservoirs.
Q. Write a short note on nuclear energy.
Answer: Nuclear energy is obtained through nuclear fission, where the nucleus of uranium or plutonium atoms is split, releasing a large amount of energy. Nuclear energy is efficient, requiring small amounts of fuel, and does not emit greenhouse gases. However, it produces hazardous radioactive waste and poses safety risks like radiation leaks and accidents.
Q. What is biogas and how is it produced? Answer : Biogas is a mixture of gases produced from the decomposition of organic matter in the absence of oxygen. It can be used for cooking and lighting.
12. Why is biogas considered a clean fuel?
Answer:
a) It produces no smoke or harmful gases during combustion.
b) Its primary component, methane, burns cleanly.
c) Reduces dependency on firewood, preventing deforestation.
d) The by-product (slurry) serves as organic manure.
Q. Explain the working of a wind turbine.
Answer : Wind turns the blades of a wind turbine, which rotates a generator to produce electricity.
13. Name three forms of ocean energy. How is each harnessed?
Answer:
1. Tidal Energy:
Harnessed by constructing dams across tidal basins to generate electricity during high and low tides.
2. Wave Energy:
Captured using devices that convert wave movements into electrical energy.
3. Ocean Thermal Energy:
Utilized by Ocean Thermal Energy Conversion (OTEC) plants, which use temperature differences between surface and deep seawater to generate electricity.
Q. What is geothermal energy? State its uses.
Answer:
Geothermal energy is the heat obtained from the Earth's interior. It is harnessed by drilling deep wells to bring steam or hot water to the surface, which is then used to generate electricity or for direct heating purposes.
Q. What are the advantages of nuclear energy?
Answer: High energy output, low fuel consumption, minimal greenhouse gas emissions.
Q. What are the disadvantages of nuclear energy?
Answer : Risk of nuclear accidents, radioactive waste disposal, potential for nuclear weapons proliferation.
Q. Why is energy conservation important?
Answer: To reduce dependence on fossil fuels, protect the environment, and ensure sustainable energy for future generations.
Q. What are the qualities of an ideal source of energy?
Answer:
A) High energy output p
er unit mass or volume.
B) Economical and cost-effective.
C) Easily accessible and available.
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