Physics Ekra banu ch heat Energy flow in an ecosystem

A source of energy is one which provides adequate amount of energy over a long period of time .
A good source of energy would be one :
Which would do a large amount of work per unit volume or mass
Which would be easy to transport from one place to another
which would be easily accessible
Which would be economical.
The sources of energy can be classified into two forms :
Renewable or non -conventional sources of energy , and
Non -renewable or conventional sources of energy .
Renewable or non -conventional sources of energy
A natural source providing us energy continuously is called a renewable source of energy.
These sources of energy can be used again and again and will never get exhausted . They are also called the non -conventional sources of energy

1. Energy flow in an ecosystem Energy is needed for all biological activities. The light from the sun is used as follows : Plants absorb most of the light falling on them in the form of energy .Of this absorbed energy,only 0.02% is used in photosynthesis.

2. Food chain Th e food chain begins with the producers and ends with tertiary consumers .

3. Energy Flow

4. The energy flow in an ecosystem is linear and shown below :

5. Sources of energy A source of energy is one which provides adequate amount of energy over a long period of time . A good source of energy would be one : Which would do a large amount of work per unit volume or mass Which would be easy to transport from one place to another which would be easily accessible Which would be economical. The sources of energy can be classified into two forms : Renewable or non -conventional sources of energy , and Non -renewable or conventional sources of energy . Renewable or non -conventional sources of energy A natural source providing us energy continuously is called a renewable source of energy. These sources of energy can be used again and again and will never get exhausted . They are also called the non -conventional sources of energy .

6. The main sources of renewable energy are •Sun Sun is the most powerful source of radiation energy. The solar energy reaching unit area at outer edge of the Earth's atmosphere exposed perpendicularly to rays of sun at average distance between earth and sun is known as solar constant . It's value is approximately equal to 1.4kJ per second per m³ or 1.4 kW/m³. Wind : •The large mass of flowing air is called wind . It possesses kinetic energy due to its motion and this energy is called wind energy. Flowing water as source of energy: The kinetic energy possessed by flowing water is called hydro energy . Biomass as a source of energy : The wastes and dead parts of living beings like plants , trees and animals is called bio mass . They contain carbon compounds . The chemical energy stored in the bio mass is called bio energy Tides as source of energy The energy possessed by rising and falling water in tides is known as tidal energy . Geo thermal spots as a source of energy: The heat possessed by rocks inside the earth is called geo thermal energy.

7. Non-renewable sources of energy • The sources of energy which have accumulated in nature over a very long period and cannot be quickly replaced when exhausted are called non -renewable or conventional sources of energy. The main sources of non renewable energy are: Coal Coal is a non renewable substance made up of complex compounds of carbon, hydrogen and oxygen along with some free carbon and compounds of nitrogen and sulphur . Petroleum It is a complex mixture of many hydrocarbons with water salt . It is found under the earth's crust in rocks . It is called petroleum because petroleum means Rock oil. Natural gas Natural gas is found deep under the earth's crust either alone or above the petroleum reservoirs .The main component of natural gas is methane along with small quantities of Ethane and propane.

8. Thermodynamics The scientific study of the relations between heat and other forms of energy is known as thermodynamics. Laws of thermodynamics 1. The first law states that the energy can neither be created no be destroyed , it can be changed from one form to another only . 2. The second law of thermodynamics stated that the heat energy cannot be transferred from a body at lower temperature to a body at higher temperature without the addition of energy .

9. Production of electricity from solar energy The arrangement of solar cells is known as solar pannel. Semiconductor like silicon and gallium are used . Silicon has a high conversion efficiency that allows more sunlight rays to become electricity . and it is durable which allows solar pannels to be warrantied for 25+ years . Solar power plant : A solar power plant is a device in which heat energy of sun is used to generate electricity. The phenomenon is known as photoelectric effect

10. Production of electricity from wind energy When the wind strikes the blade of the windmill , the kinetic energy changes into rotational energy . The rotation of the blades of turbine rotates the armature of the Dynamo .

11. Production of electricity from hydro energy Potential energy is converted into kinetic energy

12. Production of electricity from nuclear energy Nuclear is generated in a process called nuclear fission . Cadmium rods reaction rate of nuclear fission in a nuclear reactor by absorbing neutrons .

13. Green house effect Green house effect is the process of warming of the Earth's surface and it's lower by absorption of infrared radiations of long wavelength emitted out from the surface of the earth by green house gases such as carbon dioxide , mathane , nitrous oxide , ozone , chlorofluorocarbons (CFCs ) etc

14. Global warming The increase of temperature in the earth's surface is known as global warming . Energy degradation The gradual decrease of useful energy due to radiation loss , friction , etc is called degradation of energy .