1. SubScience
Std-8th
Topic – 10
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2. Introduction
10.1
10.2
10.3
10.4
10.5
10.6
10.7
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Fossil fuel
Forms of fossil fuel
Sun
Solar cooker & Solar heate
The solar cell
Other sources of energy
Atomic energy
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3. ENERGY
The capacity to do work
is called energy.
Although energy has
many forms ,it can be
changed from one form into
another.
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4. A substance that
produced energy on
burning is called fuel.
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5. A lakes of years ago because of
different calamities ,remnants of
plants and animals got buried into
the earth. Due to effect of the
tremendous pressure of layer of the
earth above the heat inside they
were converted into fuel. Such fuels
are called fossil fuel
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6. Fossil fuel formation
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7. Forms of fossil fuelSolid
Fossil Fuel
Liquid
Gaseous
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8. 1.SOLID FUEL
It was made from
remains of plants.
Firewood and brushwood
are used in rural areas.
Charcoal is formed when
wood is burnt in insufficient
air. Charcoal burns smoke
less.
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9. 2.LIQUID
Mineral oil is found nearly 25,000
meters deep in the bowels of the
earth.
Petrol, diesel, kerosene and fuel oil
can be obtained from it .
70 percent mineral oil we use.
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10. 3. GASEOUS
•Natural gas is lights up quickly and burns
without leaving behind any solid
substances. Besides, it is easy to transport
form its main source by means of pipes
over long distances. A big advantage is
that the burning of natural gas can be
easily controlled.
•Ex. methane [CH4], ethane[C2H6],
propane[C3H8], butane[C4H10], etc.
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11. Sun
The earth gets a tremendous
amount of energy from the
17
sun as much as 7 x 10
kilowatts per year.
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12. Std-8th
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13. Std-8th
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14. Solar cooker and
solar heater
In this devices, mirrors are used
to collect and concentrate solar
energy.
It can be used to cook food or
heat water, etc.
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15. Std-8th
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16. Solar cell
In the solar cell, solar energy
is converted into electric
energy and this can be used
at night for lighting.
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17. Fossil fuel
They cannot be produced a
new, therefore, they are called
to be conventional or nonrenewable sources of energy.
There are only limited
deposits of fossil fuel.
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18. Solar energy
•It is always available, so
they are called nonconventional or renewable
source of energy.
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19. Other sources of energy
Wind energy,
hydro- electric energy,
biogas,
bio-diesel
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20. Std-8th
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21. Std-8th
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22. Std-8th
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23. Problem created by using
conventional sources of energy
• Global warming – Gases like carbon-dioxide,
carbon-monoxide, hydrogen sulphide causes
problem of population.
• Pollution – Carbon-dioxide and many other
gases causes problem of pollution.
• Depilation of ozone layer- gases like CFC
causes holes in ozone layer of atmosphere.
• Deforestation-Due to cutting trees causes
number of forest become dwindled.
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24. Creation
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