Alternate Sources of Energy-10th Science Notes

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Chapter-1

Alternate Sources of energy

Text book question and answers

I. Choose the correct answer from those given, for the following questions

1. Identify from the following a conventional source of energy

(a) Solar energy (b)tidal energy (c)natural gas (d)bio energy

Answer: (c)natural gas

2. The largest installation of wind turbines in our country is in

(a)Ladakh (b)Gujarat (c)Kanyakumari (d)Madhya Pradesh

Answer: (c) Kanyakumari

3. Which of the following is not a feature of bio energy?

(a) It improves soil quality (b) It enhances water retention

(c) It reduces carbon dioxide content in the atmosphere

(d) It increases pollution

Answer: (d) it increases pollution

4. Which of the following is an indirect form of solar energy?

(a)tidal energy (b) energy from wastes (c) geothermal energy (d) electricity

Answer: (a) tidal energy

 

II. Fill in the blanks with suitable words.

1. The principle involved in the conversion of solar energy into electrical energy is called Photo Voltaic Effect.

2. The conversion of crude oil from plant seeds into a useful fuel involves a process called Trans esterification.

3. Wind energy is a converted form of Solar energy.

4. The energy trapped within 10km of Earth’s crust is known as geothermal energy.

 

III. Answers the following questions.

1. What is the need for exploring alternative sources of energy?

The conventional sources of energy like coal and petroleum that are being used for a long time are non-renewable and their reserves are depleting at a fast rate. However, the demand for energy is increasing hence there is need for exploring alternative sources of energy.

2. Make a list of the advantages of non-conventional sources of energy.

The advantages of non-conventional sources of energy are

1. They are abundant

2. They are renewable

3. They are pollution free

4. They are eco-friendly

3. Differentiate between solar collectors and solar cells.

Solar collectors

Solar cells

1. Any device that absorbs and accumulates solar energy in the form of heat is called a solar collector

2. Solar collector can be used for heating water, cooking food, drying of food grains and vegetables, seasoning of wood and desalination of marine water.

1. Devices made from silicon or germanium, which convert solar energy into electric energy using the principle of photo voltaic effect are called solar cells.

2. Solar cells can used in traffic signals in cities, lighting lamps and pumping water and for other purposes in rural areas.

4. What is bio energy?

The energy obtained from biological matter such as plants and plant products is bioenergy.

or

Bioenergy is energy derived from biomass which includes biological material such as plants and animals, wood, waste, (hydrogen) gas, and alcohol fuels

5. Name any two plants that are sources of biofuel.

Two plants that are sources of biofuel are

1. Jatropha

2. Pongamia pinnata (Honge)

6. Write a brief note on geothermal energy.

Geothermal energy refers to heat of the Earth within 10km. from the surface. It can also be processed for power. Geothermal energy has a temperature of about 13000c

There are about 340 hot springs identified in different parts of our country. Of these, only a few have been used. There have been attempts to utilize the geothermal energy in puga, Manikaran, Tatapani and Bakneshwar.

 

Additional Question and Answers

1. What are renewable sources of energy? Give examples

Some of the energy sources can get replaced in nature easily such sources of energy are called renewable sources of energy.

Examples of renewable sources of energies are: Sun, Wind, Tides, Geothermal sources, biomass and energy from wastes

2. What are non-renewable sources of energy? Give examples

Some sources of energy which cannot be replenished once depleted are called non-renewable sources of energy.

Examples of non-renewable sources of energies are

Coal, Petroleum, Natural gas and Electricity

3. What are conventional sources of energy? Give examples

Non- renewable sources of energy which we have been using since a long time are known as conventional sources of energy.

Examples of conventional sources of energies are: Coal, Petroleum, Natural gas and Electricity

4. What are non-conventional sources of energy? Give examples

*Renewable sources of energy which are available on the earth and which can serve as alternatives to conventional sources of energy are known as non-conventional sources of energy

Examples of non-conventional sources of energies are

Sun, Wind, Tides, Geothermal sources, biomass and energy from wastes

* Renewable sources of energy are known as non-conventional sources of energy.

* Non-renewable sources of energy are known as conventional sources of energy.

* Alternate sources of energy are known as renewable sources of energy.

5.  Sate the purposes served by the use of non-conventional sources of energy.

The use of non-conventional sources of energy can serve the following two main purposes

1. Energy can be supplied to the consumers in a decentralized system, and

2. It is possible to sustain a cleaner environment

6. What is solar energy?

Radiant energy emitted by the sun is called solar energy

Radiant energy of the sun in the form of light and heat

7. What is the sources of energy of the sun?

The enormous amount of energy of the sun is due to continuous thermonuclear fusion reactions taking place in the interior of the sun.

8. Define photon

Solar energy (Light) Stored in the form of small wave packets are called photons.

Or

A tiny packet of energy associated with light is called a photon

9. Define solar constant. State its value.

The amount of solar energy reaching per square meter of Earth’s atmosphere is called solar constant

The value of solar constant is about 1.36 kilo watt or 1360 watt per square metre.

10. What is the distance between the sun and earth?

The distance between the sun and earth is about 150 million kilometre.

11. Write the applications of Solar energy

There are three main applications of solar energy.

1. Collecting and Converting Solar energy into heat energy using solar collector

2. Conversion of solar energy into electrical energy using solar cells

3. The natural conversion of solar energy into biomass which in turn serves as a source of energy

12. What is a solar collector? Write its applications

Any device that absorbs and accumulates solar energy in the form of heat is called a solar collector

Applications:

1. Solar cookers

2. Solar hot water systems

3. Solar dryers

4. Solar air heaters

13. Write the uses of Solar heaters

1. Drying of food grains and vegetables

2. Heating of water

3. Cooking of food

4. Seasoning of wood and desalination of marine water

14. What is a solar pond? Write its uses.

A solar pond is a pool of saltwater which acts as a large-scale solar thermal energy collector with integral heat storage for supplying thermal energy.

A solar pond can be used for various applications, such as process heating, desalination, refrigeration, drying and solar power generation.

India was the first Asian country to have established a solar pond in Bhuj in Gujarat. It is designed to supply about 220 lakh kwh of thermal energy annually.

15. What is solar cell?

Devices made from silicon or germanium, which convert solar energy into electric energy using the principle of photo voltaic effect are called solar cells.

16. What is photovoltaic effect?

The photovoltaic effect is the creation of voltage or electric current in a material upon exposure to light and is a physical and chemical phenomenon

17. Write the Advantages of Solar Energy

1. After initial investment, all the electricity you produce is free.

2. It is abundant.

3. It is everlasting.

4. It is available almost everywhere.

5. It is free from political barriers.

6.  Incentives and rebates from governments and utility companies offset the initial investment.

7. Reduce or completely eliminate your electric bill.

8. Cost of solar panels are decreasing while efficiency is increasing.

18. What is Biomass?

Biomass is biological material derived from living, or recently living organisms

19. Write the uses of Bio energy?

1. Maintains an unpolluted environment

2. reduces the carbon dioxide content in the atmosphere

3. Improves quality and water retention capacity of the soil.

20. What is Biogas? Mention its chief constituents

A combustible gas produced by the anaerobic decomposition of biomass is known as biogas. The chief constituents of biogas are methane and hydrogen

* Biogas is a clean, unpolluted and inexpensive source of rural areas. It contains nearly 70% of methane, an inflammable gas; it is produced from cow dung in a specific biogas plant commonly called gobar gas plant. It helps in obtaining both cooking fuel and enriched manure. It can use for lighting and running small engines.

21. How is biomass converted into energy?

There are three basic processes involved in the conversion of biomass into energy sources.

1. Combustion pyrolysis: It is a process of chemical decomposition at high temperature (as high as 50000c) in total or partial absence of air. It yields fuel gas, ethanol and charcoal.

2. Bio gasification: It is process of anaerobic digestion of biomass to produce a combustible gas called biogas, containing methane and hydrogen.

3. Fermentation: conversion of sugars into alcohol to produce ethane and solid residual fuel.

22. What is trans esterification?

Trans esterification is the process conversion of crude oil from the seeds to a commercially useful fuel.

1. Trans esterification has been standardised by the scientists at Indian Institute of Science Bangalore.

2. Bio fuel is alternative to diesel

3. Bio fuel is used to run transport vehicles

23. Write the Advantages of Bio-diesel.

1. It is an agriculture based fuel substitute.

2. It can be made from both vegetable oil and animal fats.

3. It can be used without major modifications in engines.

4. It does not need separate infrastructure for storage and delivery.

5. Handling bio-diesel is safer.

6. Its combustion emits less carbon monoxide, sulphates, unburnt hydrocarbons and particulate matters, thus reduces air pollution.

24. Write the advantages of Biogas

1. Clean, non-polluting and cheap

2. Direct supply of gas from tank.

3. No maintenance cost

4. Does not cause any health hazard.

5. Provides us both the fuel and the manure.

25. Write a note on wind energy.

1. Airflows can be used to run wind turbines.

2. Wind energy is used in wind mills which converts the kinetic energy of the wind into mechanical or electrical energy.

3. The kinetic energy of wind can be used to do mechanical work like lifting water from wells or grinding grains in flour mills.

4. A single wind mill produces only a small amount of electricity.

5. Large number of wind mills in a large area are coupled together to produce more electricity in wind energy farms.

6. The minimum wind speed required is15km/hr.

7. Speed of wind should be between 8 and 22m per sec.

8. Wind turbines are used for the purposes of obtaining wind energy.

9. At present Wind power potential of India is 1020 MW

10. Largest wind farm is near Kanyakumari in Tamilnadu generate 380 MW electricity

26. What is wind mill?

A structure that has parts which are turned around by the wind and used to get certain work done is called a wind mill

27. What does a windmill do?

A wind mill converts the kinetic energy of the wind into mechanical or electrical energy

28. Write the advantages and disadvantages of wind energy

Advantages:-

1. It is a renewable source of energy.

2. It does not cause pollution.

3. The recurring cost is less.

4. Once the wind turbine is built the energy it produces does not cause greenhouse gases

Disadvantages:-

1. Wind is not available at all times.

2. It requires a large area of land.

3. A minimum wind speed of 15 km/h is required.

29. Write a note on wave energy.

Movement of large quantities of water up and down in the seas and oceans, in the form of waves is also a source of energy. This energy can be converted into mechanical energy and electrical energy. The tropical coastline of our country especially the south west coast line is found to be highly suitable for establishing energy conversion plants. However, the cost of energy conversion per unit is very high since it requires many special equipment’s to be created near the sea. Wave energy is however more reliable than wind energy since the fluctuations are comparatively less pronounced.

Or

1. Produced by gravitational forces of sun and moon.

2. Produced by making the use of water movement from a high tide to a low tide.

3. The high tide to a low tide refers to the rise and fall of water in the ocean.

4. A difference of several meters is required between the high and low tide.

5. Ocean waves and tides can be made to turn a turbine and generate electricity.

6. Areas where rivers flow into the sea experience waves and tides and electricity can be generated there. It has much potential.

7. As you know we have a large coastline and major river systems in our country, electricity can be generated on a large scale from waves and tides.

8. The periodic rise and fall of sea level due to gravitational attraction of the moon causes tides.

9. A Tidal barrage is constructed at a narrow opening between the land and sea.

10. The movement of water during high tide and low tide can be used to rotate the turbines of generators to produce electricity.

11. Tidal power site In india :-gulf of cambay, gulf of Kutch and the sunder bans delta.

30. Write a note on Geothermal Energy

1. It means the energy harnessed from the hot rocks present inside the earth.

2. High temperature, high pressure steam fields exit below the earth’s surface in many places.

3. At the core, temperatures may reach over 9,000 degrees Fahrenheit.

4. This heat comes from the fission of radioactive material naturally present in the rocks.

5. The deeper regions of the earth’s crust is very hot. This heat melts rocks and forms magma.

6. The magma moves up and collects below at some places called Hot spots.

7. The underground water in contact with hot spot gets heated into steam at high pressure.

8. By drilling holes into hot spots the steam coming out can be used to rotate turbines of generators to produce electricity.

9. There are 46 hydrothermal areas in India where the water temperature normally exceeds 150 degree centigrade.

10. Electricity can be generated from these hot springs.

11. In many places the the hot water comes out of the ground through cracks in the form of Natural geysers:E.g. Manikaran, Kullu and sohana, Haryana.

12. Earth's geothermal energy originates from the original formation of the planet (20%) and from radioactive decay of minerals (80%). 

31. Write a note on energy from wastes.

A huge quantity of waste is generated in our towns and cities. Waste generation is very high, especially in sugar, paper and pulp industries. Such wastes can also be converted into energy.

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2 comments

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21 July 2014 at 08:59 delete

Sir U had made good notes. Thankas & congrats forever.

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21 July 2014 at 09:03 delete

sir please , if any more information on science syllabus give us. How I collect in Kannada version.

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