SOURCE OF ENERGY (2). optic for class 12 only

Rhrh

1. SUN is the main source of energy for us on the EARTH . SUN as the source of energy The energy obtained from the sun is called Solar Energy .

2. INTERIOR OF THE SUN

3. Since the Sun is very far from the Earth , we receive only few amount of total solar energy

4. USE OF SOLAR ENERGY The solar energy absorbed by land and water bodies causes storms , rains , snow falls etc .

5. 2. Wind as a source of Energy The large mass of moving air is called wind . Due to motion it has kinetic energy . The kinetic Energy of wind is called Wind Energy .

6. Reason of WIND Indirectly wind energy comes from solar energy . The sun rays falling on the earth heat different areas of the earth unequally . Due to Unequal heating of different areas of the earth . rotation of the Earth . local convection current . We have different wind cycles

7. USES removing husk from grain propelling sail boats in the rivers and seas in moving vehicles for transportation In windmills to draw water from the ground and to grind grains .

8. 3.FLOWING WATER AS A SOURCE OF WATER The kinetic Energy possessed by the flowing water is called hydro energy . REASON The hydro energy too comes indirectly from the sun . The Sun is responsible for water cycle .

9. USES rotating the wheels of water mills used to drive the flour mill in remote hilly areas . for the tranporting of heavy logs of wood from forests in hilly areas to the downstream areas in plane .

10. 4. Biomass as the source of energy The wastes and dead parts of living beings like plants , trees and animals is called biomass . They contain Carbon Compounds . The chemical energy stored in biomass is called bio energy .

11. USES Biomass such as wood , cattle dung , crop residues and agriculture waste such bagasse has been traditionally used as fuel to produce heat energy for domestic as well as commercial purpose .

12. Biogas Biomass is also used to produce biogas by its decomposition in the presence of oxygen Constituent of Biogas Methane [ 65%] Rest is a mixture of carbon dioxide , hydrogen and hydrogen sulphide .

13. Types of biogas plant The floating gas holder type The fixed dome type They are also called gobar gas plants because the main biomass used in these plants is called slurry which is the mixture of animal dung [ or gobar ] in water .

14. 5. Tides as the source of Energy The rise of ocean water near the coast is called high tide And fall of ocean water is called low tide . This rise and fall of tidal waves occurs twice a day in oceans . The energy possessed by rising and falling water in tides is known as tidal energy.

15. Tidal energy is harnessed for producing electricity by constructing a dam across a narrow opening to the sea Not the major source because 1. rise and fall number is less 2. Few suitable sites .

16. 6. Ocean as source of energy Water in the ocean possesses energy in two forms Ocean Thermal Energy Ocean or sea waves energy

17. 1. Ocean thermal energy water at the top surface get heated due to sun while water at its deeper remains cold There is the difference upto 20 degree C The energy available due to the difference in temperature of water at the surface and at deeper levels of oceans is called thermal energy [ OTE ] . Device name – [OTEC] ocean thermal energy conversion power plant .

18. 2. Oceanic [ or sea ] waves energy Due to wind blowing on the surface of oceans , waves , move at high speed on its surface which are called oceanic waves or sea waves Due to their high speed they carry tremendous amount of kinetic energy with them Thus , the kinetic energy possessed by such fast moving oceanic [ or sea ] waves is called oceanic waves energy . USES : To generate Electricity.

19. 7. Geothermal spots as source of Energy At some places rocks below the surface of the earth are very hot . Such places are known as Hot Spots . The Heat energy possessed by rocks inside the earth is called Geothermal Energy .

20. USES By drilling holes into the Earth up to the hot spots , steam is extracted through pipes which is utilized to rotate the turbine connected to the armature of an electric generator to produce electricity. Plant is in Madhya Pradesh

21. 8.Nuclear fuel as a source of energy When uranium nucleus is bombarded with a slow neutrons , it splits into two nearly equal light nuclei and a large amount of energy is released . The phenomenon is called Nuclear fission .

22. In fission reaction of one uranium nucleus , nearly 200 MeV energy is released and two to three neutrons are also emitted . If large number of uranium nucleus is present then chain reaction starts which ends till all the uranium is exhausted . Due to this uncontrolled chain reaction it can cause explosion . [ This process is used in atom Bomb ] This Energy is used in constructive use to generate the electricity. Note : This reaction is control by controlling the neutrons by absorbing the neutrons with the help of cadmium rod . This is done in nuclear reactor .

23. Nuclear Fusion Similarly when two light nuclei combine to form a heavy nucleus at a very high temperature [107 K ] and high pressure , a high amount of energy is released . This phenomenon is called nuclear fusion

24. E=mc 2 In both the process the origin of energy is the loss of mass Mass of Reactant >Mass of Product Mass is converted into Energy according to Einstein’s mass – Energy equivalence relation E = m c 2 Where m = loss in mass , c = speed of light.

25. Non –Renewable Source of Energy OR Conventional source of Energy The source of Energy which have accumulated in nature over a very long period and cannot be quickly replaced when exhausted . NOTE : Coal, Petroleum , And natural gas known as fossil fuels . Fossils fuel : They are formed by the decomposition of remains of plants and animals buried under the earth , millions of years ago .

26. 1. Coal Coal is a non – renewable source of energy made up of complex compounds of carbon, hydrogen and oxygen along with some free carbon and compounds of nitrogen and sulphur . Found in deep mines under the Earth . Coal Mines – Jharkhand , West Bengal , Odisha Chhattisgarh .

27. 2. Petroleum Petroleum is dark colored viscous liquid . It is also called Crude Oil . It is a complex mixture of many hydrocarbon with water , salt , earth particles and other compounds of carbon , oxygen , nitrogen and sulphur . Lighter than water and do not mix with water . Petroleum is obtained by drilling oil wells into the Earth’s crust . Not suitable to use a fuel in its natural form .

28. Refining The process of separating useful components from crude petroleum is called refining which is done by fractional distillation in big oil refineries set up for this purpose .

29. Petroleum Gas – Mainly butane and small amount of propane and ethane . The Petroleum gas liquefied under pressure is called pressure is called liquefied petroleum gas (LPG) . Which is used in domestic gas stoves as fuel for cooking purpose . Note : Mixing with strong smelling agent ethyl mercaptan C 2 H 5 SH for the leakage of gas . LPG

30. 3. Natural Gas It is found deep under the earth’s crust . The main component is methane about 95% with small quantity of ethane and propane .

31. Production of Electricity from Solar To obtain electricity from solar energy , two devices are used : Solar cell Solar energy Electric Energy Solar power plant Solar Cell Sunlight falls on thin layer of selenium . Only 0.6% of the solar energy converted into electric energy Solar cells are made up of semiconductors like silicon and gallium . Order Of conductivity - Insulator < Semiconductor < Metals Methods of increasing conductivity of semiconductor – Increase in temperature adding impurity ( doping ) Due to falling of sunlight potential difference generates which results in production of current . Large number of solar cells are arranged to form solar panel. Secondary Cells ( storage battery )are connected to overcome the problem of charging at night . Small solar cells are used in watches and calculators

32. ADVANTAGES : Not require any maintenance They last over for a long period Running coast is nil. Pollution Free DISADVANTAGES : Initial coast is high . Efficiency is low Solar Energy produces DC which cannot be used directly for household work .

33. Solar Power Plant A solar power plant is a device in which heat energy of the sun is used to generate electricity . The sun rays after reflection from a large concave reflector get concentrated at its focus . The rays have sufficient heat energy which can boil water if it placed at the focus . This principle is used in solar power plant . Sun Rays – Concave Reflector – Black painted pipes – water start to boil – steam helps to move the turbine – produces electricity .

34. PRODUCTION OF ELECTRICITY FROM WIND ENERGY