Wednesday, August 15, 2012

CBSE Pathshala :X Physics Ch- Sources of Energy – Extra scoring notes

X Physics Ch- Sources of Energy – Extra scoring Notes Part -1 
Energy is the capacity of a body for doing work. We have a wide range of sources of energy such as the sun, the wind, the earth geothermal), flowing water, coal, gasoline, diesel, natural gas, biogas, etc. at our disposal.
There are two types of sources of energy:
Renewable sources of energy (or non-conventional sources of energy): The sources of energy which are in constant supply to us by nature and are inexhaustible are known as renewable sources of energy. Example : The sun (solar energy), oceans, tidal energy, wind energy, running water energy, wood, geothermal energy etc.
(ii) Non- renewable sources of energy (or conventional sources of energy): The sources which cannot used again and again and are exhaustible are known as non-renewable sources of energy. Example: Coal, natural gas, petroleum, fossil fuels etc.
A good fuel:
(a)Low ignition temperature (ii) having high calorific value (iii) Produce less fume and pollutants
A good source of energy has following characteristics:
(i) Provide large amount of energy                     (ii) Easy to store and  transport
(iii) Economical                                                        (iv)  Easily available
Q. If you could use any source of energy for heating your food, which one would you use and why?
Ans: LPG or Natural as it is highly inflammable, produce less smoke on burning, easy to use, transport and Having high calorific value
Fossil Fuels: It takes million of years to form by carbonization e.g. coal, petroleum and natural gas. The oxides of carbon, nitrogen and sulphur are released on burning fossil fuels are acidic oxides that when mixed with rain lead to acid rain. Excess of carbon mono oxide also create green-house effect.
Fossil fuels are the major fuels used for generating electricity in thermal power plants.  Stem produced has energy that work to rotate the fan, the rotor blade of dynamo with high speed and convert the mechanical energy into electrical energy.
The disadvantages of fossil fuels :
( a) produces a lot of pollutants that cause air pollution.
(b) Cause acid rain and global warming that affects the soil fertility and drinking water and temperature above land.
Hydro Power Plants : The kinetic energy of flowing water or the potential energy of water at a height can be utilized to moves the turbine which in turn rotate the coils of an electrical generator to produce power or electricity at hydroelectric power stations. Hydro energy can be stored by storing water in high altitude dams. Hence it is a renewable source of energy
Advantage of Hydro electricity:
(a) The process of hydel power does not cause any environment pollution.
(b) The moving water needed for the purpose is available free of cost.
(c) Water energy is a renewable source of electrical energy which will never get exhausted.
(d) The construction of dams on rivers helps in controlling floods and in irrigation.
Disadvantages of Hydro electricity:
(a) The construction of dam on a river disturbs the ecological balance
(b) Land for agricultural and human habitation submerged in the constructions of big dams.
(c) Dead plants and animals submerged into water produce methane gas cause green house effect.
(d) Decrease fertility of soil in downstream area
Q. Why are we looking at alternate sources of energy?
Ans: Traditionally used sources of energy are limited and used at large scale. If this rate of consumption continues, then the fossil fuels would be run out from the Earth. Therefore, we need to conserve the energy sources. Hence, we are look for alternate sources of energy.
Biomass: Biomass is a renewable source of energy because it is obtained from plants (or animals) which are produced again and again.
There are two ways of using biomass as a fuel. One is to burn the dry biomass like cattle-dung or wood directly to produce heat. Another method is to convert the biomass into charcoal and Biogas which is comparatively smokeless and has a high calorific value. Biomasses produce less heat with a lot of smoke on burning.
Wind Energy: This kinetic energy of moving air rotate windmill that is used to turn the turbine of the electric generator to produce electricity. Wind energy is an environment-friendly and efficient source of renewable energy.
Disadvantages of Wind Energy:
(i) It may not be available at all times.                       (ii) Need large open space
(iii) it is costly                                                              (iv) Require high maintenance
Solar energy: The energy generated by the sun is the result of reaction called nuclear fusion.

1 comment:

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