Chapter 14 Sources of Energy Class 10 Science Extra Questions
Chapter 14 Sources of Energy Extra Questions and Answer
Chapter Name | Sources of Energy Extra Questions |
Class | CBSE Class 10 |
Textbook Name | Sources of Energy Class 10 |
Related Readings |
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Very Short Answer Type
Question 1. Define fossil fuel.
Answer
Fossil fuels were formed millions of years ago, when plants and animal remains got buried under the earth and were subjected to high temperature and pressure conditions. For example, Coal, Petroleum, etc.
Question 2. Write down the disadvantages of fossil fuels.
Answer
These fossil fuels are non-renewable sources of energy and cause environmental problems due to pollution.
Question 3. Define Nuclear energy.
Answer
Nuclear energy: Energy released when some changes take place in the nucleus of the atom of a substance, is called Nuclear energy.
Question 4. Define solar cell.
Answer
Solar cell is a device that converts solar energy into electricity.
Question 5. Define non-conventional sources of energy.
Answer
Non-conventional sources of energy are those which are not used as the conventional ones and meet our energy requirement only on a limited scale.
Examples:
- Tidal energy
- Geothermal energy.
Question 6. Define conventional sources of energy.
Answer
Conventional sources of energy are those which are used extensively and meet a major portion of our energy requirement.
Examples:
- Fossil fuels
- Hydropower plants.
Question 7. How is charcoal produced and what is the advantage of charcoal in comparison to wood?
Answer
When wood is burnt in a limited supply of oxygen, the volatile materials present in it get removed, and charcoal is produced. Charcoal bums without flames and is comparatively less smoky.
Short Answer Type
Question 1. Write down the characteristics of a good fuel.
Answer
Characteristics of a good fuel:
- Has high calorific value
- Produces less smoke
- Produces less residue after burning
- Easy availability
- Inexpensive
- Easy to store and transport
Question 2. What is a thermal power plant?
Answer
In a thermal power plant
- Coal, petroleum and natural gas is used to produce thermal electricity.
- Electricity transmission is very efficient.
- The steam produced by burning fossil fuels runs the turbine to produce electricity.
Question 3. Write down the advantages and disadvantages of a nuclear power plant.
Answer
Advantage of Nuclear energy:
- Alternative source of energy due to depletion of fossil fuels.
- From a small amount of fuel, a large amount of energy is released.
Disadvantages of nuclear energy:
- Difficult to store and dispose nuclear waste which may cause environmental contamination.
- High cost of setting up a nuclear plant.
- Limited availability of raw material (uranium).
Question 4. Describe energy harnessed from wind and write down its advantages and disadvantages.
Answer
Wind energy:
- It can converted into mechanical and electrical energy.
- Kinetic energy of the wind is used for running windmills, which can be used to lift water, grind grains, etc.
Advantages:
- Eco friendly
- Renewable
Disadvantages:
- Wind speed not uniform always.
- Needs a large area to erect series of windmills.
- Big amount of investment is needed.
- Output is less as compared to investment.
Short Answer Type II
Question 1. How can solar energy be harnessed? Mention any two limitations of using solar energy. Write down the advantages of solar cell.
Answer
Solar energy:
Solar radiations can be converted into electricity through solar cells (photovoltaic cells). Photovoltaic cells convert solar radiations directly into electricity through silicon solar cells. Solar cells are arranged on large flat sheets to form a solar panel.
Advantages of solar cell:
- Solar cell have no moving parts, require little maintenance and work quite satisfactorily.
- They can be setup in remote and inaccessible hamlets or very sparsely inhabited areas.
Limitations:
- Solar cells are expensive.
- Solar devices are only useful during day time and on a sunny day.
Question 2. Write two different ways of harnessing energy from the ocean.
Answer
Energy from the sea:
1. Tidal energy
Locations in India – Gulf of Kutch, Gujarat and West Bengal
- Depends upon harnessing the rise and fall of sea level due to tidal action.
- Dams are constructed across a narrow part of sea the and a turbine converts tidal energy into electrical energy.
Disadvantage: Uniform tidal action is not seen.
2. Wave energy- Kinetic energy of the sea waves are used to rotate turbines.
- These turbines generate electrical energy.
Question 3. Write a short note on geothermal energy.
Answer
- Energy harnessed from the heat of the Earth is called geothermal energy.
- Magma is formed when this heat melts the rocks. The molten rocks and hot gases are called magma.
- The magma gets collected at some depths below the earth’s surface. These places are called “hot spots’.
- When underground water comes in contact with these hot spots, it changes into steam, which can be used to generate electricity.
Advantages of geothermal energy:
- Cost of production is not much.
Disadvantages of geothermal energy:
- Only few sites available for harnessing energy.
- Expensive to set up.
Long Answer Type
Question 1. What is biomass? Explain the principle and working of a biogas plant using a labelled schematic diagram. Write down its advantages.
Answer
Biomass is a source of conventionally used fuels that are used in our country, e.g., cow dung cakes, fire-wood, coal, charcoal.
Biogas: It is a mixture of gases produced during the decomposition of biomass in the absence of oxygen.
Methane is the major component of biogas. (Biogas contains 75% methane, carbon dioxide, hydrogen and hydrogen sulfide).
Biogas plant: Animal dung, sewage, crop residues, vegetable wastes, poultry droppings, etc. are used to produce biogas in biogas plants.
Construction and working:
The plant has a dome-like structure built with bricks. A slurry of cow dung and water is made in the mixing tank from where it is fed into the digester. The digester is a sealed chamber in which there is no oxygen. Anaerobic microorganisms, that do not require oxygen, decompose or breakdown complex compound of cow dung slurry and produce methane, carbon dioxide, hydrogen and hydrogen sulfide.
Advantages of biogas
- It bums without smoke and leaves no residue.
- Its heating capacity is high.
- The slurry of biogas plant is used as an excellent manure, rich in nitrogen and phosphorus.
Question 2. Write down construction, advantages and limitations of a solar cooker.
Answer
Solar cooker:
Construction:
Outer surface of the solar cooker is painted with black colour and a glass plate is used as cover.
Black colour absorbs more heat and the glass plate traps solar radiation by greenhouse effect. Mirror reflects the light.
Advantages of solar cookers
- Eco friendly
- Renewable
- Used in rural areas.
- Retains all the nutrients in food due to slow cooking.
Disadvantages of solar cooker
- Silicon cells are expensive.
- Solar radiations are not uniform over the Earth’s surface.
- Cannot be used at night or on cloudy days.
- Cannot be used to make chapattis for frying as these require a temperature of 140°C or more. (Maximum temperature of 100°C only can be achieved in a solar cooker.)
Question 3. What is hydroelectric power plant? Write down its advantages and disadvantages.
Answer
Hydroelectric power plant: A conventional renewable source of energy is obtained from water falling from a great height. Dams are constructed to collect water flowing in high altitude rivers. The stored water has a lot of potential energy. When water is allowed to fall from a height, potential energy changes to kinetic energy, which rotates the turbines to produce electricity.
Advantages:
- It is clean and non polluting source of energy.
- Hydropower is renewable source of energy.
Disadvantages:
- Highly expensive to construct.
- Dams cannot be constructed on all river sites.
- Large areas of human habitation and agricultural fields get submerged.
People face social and environmental problems.
HOTS Questions With Answers
Question 1. What is the role of a plane mirror and a glass sheet in a solar cooker?
Answer
Plane mirror reflects sunlight so that maximum sunlight can enter the box.
Glass sheet traps solar radiation by greenhouse effect.
Question 2. What kind of mirror is used in concentrating type-solar cooker?
Answer
A concave mirror is used in concentrating type solar cooker so that maximum heat can be concentrated at a given point.
Question 3. Name the process that produces a large amount of energy in the sun.
Answer
Nuclear fusion
Question 4. Name the materials used for making solar cells.
Answer
Silicon, Germanium and Selenium
Value Based Questions
Question 1. A. Reddy visited his grandfather’s village Koodankular with his younger sister. They saw people protesting against building a nuclear power plant there. Reddy’s sister asked the reason for the protests. Reddy said that it could be due to the risks involved in setting up the plant near people’s habitation.
(i) Write down the advantages and disadvantages of a nuclear power plant. ‘
(ii) Values shown by A. Reddy.
(iii) Which process is used to harness nuclear energy? Explain briefly.
Answer
(i) Advantages of Nuclear energy:
- Alternative source of energy due to depletion of fossil fuels.
- From a small amount of fuel, a large amount of energy is released.
Disadvantages of Nuclear energy:
- Hazardous nature of nuclear waste and risk of nuclear waste leakage.
- High cost of setting up a nuclear plant.
- Displacement of people from their habitat.
(ii) A. Reddy is a very intelligent person.
(iii) Nuclear energy is produced by a process called nuclear fission. During this process, the nucleus of a heavy atom (such as uranium, plutonium or thorium) when bombarded with low-energy neutrons, can be split apart into lighter nuclei. The process releases a tremendous amount of heat energy. The released energy can be used to produce steam which is used to produce electricity.
Question 2. During summer vacations Bhaskar visited his uncle’s village. He saw a biogas plant installed by villagers for their basic energy needs.
(i) What is biogas and biogas plant?
(ii) What values are shown by villagers?
Answer
(i) Biogas: It is a mixture of gases produced during decomposition of biomass in the absence of oxygen. Methane is the major component of biogas.
Biogas plants: Animal dung, sewage, crop residues, vegetable wastes and, poultry droppings are used to produce biogas in biogas plants.
(ii) Villagers are intelligent and care for the environment.
Question 3. Jatin aggarwal took admission in DTO (Delhi Technological University). He saw solar devices were installed in the university.
(i) Write down a short note on solar energy and solar cooker.
(ii) Write down the values shown by the university management.
Answer
(i) Solar energy:
- Solar radiations can be converted to electricity through solar cells (photovoltaic cells).
- Photovoltaic cells convert solar radiations directly into electricity through silicon solar cells.
- Solar cells arranged on a large flat sheet to form a solar panel.
Solar cooker:
- Solar cookers are painted black from outside and covered with a large glass plate to trap solar radiations by greenhouse effect.
(ii) University management is concerned about energy conservation.