Laser ,Types and Use

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  LASER :-                    LASER is an acronym of  Light Amplification by stimulated emission of Radiation. It is an optical device which produces an intensive beam of highly coherent, Monochromatic light[ Electromagnetic radiation, especially visible radiation, of only one frequency or wavelength]. It can travel over great distance without spread.   LASER LIGHT :-                                   1. It is very different than normal light and contains only one specific wavelength of light.                                 2. A laser light has very tight beam and is very strong and concentrated.                                 3. A laser light can go to the moon and th...
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Hydro Electric power plants

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Hydro Power Plants-
                                    The power plants which converts the potential energy of falling water into electricity, are called Hydro-power plants. Electricity produced by hydro-power plants is called Hydro electricity.

 Principle-
                 To produce hydroelectricity, high-rise dams are constructed on the river to obstruct the flow of water and thereby collect water in large reservoirs.
                 
                  Due to the rise water level, the Kinetic energy of flowing water gets converted into Potential energy. 


The water from a high level is carried through the pipe to the turbine located near the bottom of the dam, which connected to an electric generator.
            When the water turbine rotates, the generator also rotates with it rapidly and produce Electricity.
        
  • Tehri Dam – Uttarakhand. ...
  • Bhakra Dam – Himachal Pradesh. ...are examples.
Advantages- 
1. It does not cause any environmental pollution. 
2. The moving water needed for the purpose is available free of cost.
3. Water is a renewable source of energy which will never get exhausted. Each time when it rains, the reservoir gets refilled.
4. The construction of dams on rivers helps in controlling flood and also in irrigation. 
Disadvantages- 
1. construction of dams may lead to ecological damage.
2. A large variety of plants, animals and their habitat gets submerged in water. 
3. It decreases the fertility of the soil in the downstream area and affects crops. 
4. Dams can be constructed only in a limited number of places preferably in hilly terrains. 
5. The vegetation that gets submerged rots under anaerobic conditions and gives rise to large amounts of methane(cH4) which is greenhouse gas. 
6. It creates the problem of rehabilitation of displaced people.
Due to such disadvantages construction of dams are opposed.
Wind energy- moving air is called wind. As the moving objects possess kinetic energy, they are capable of doing mechanical work by virtue of its motion. The energy possessed by the wind is due to its high speed.
The kinetic energy of wind is utilised for doing works like 
1. generating electricity.
2. Propelling sailboats in rivers and seas. 
3. In water-lifting pump to pump out water from the ground. 
4. Grinding grain to obtain flour.
5. Rotatory motion of windmill is used to lift water from a well.


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