 The energy in the flowing water can be used to produce electricity. Waves result from the interaction of the wind with the surface of the sea and represent a transfer of energy from the wind to the sea. Energy can be extracted from tides by creating a reservoir or basin behind a barrage and then passing tidal waters through turbines in the barrage to generate electricity.

 Although most energy in a country is produced by fossil-fuel and nuclear power plants, hydroelectricity is still important to the Nation, as about 7 percent of total power is produced by hydroelectric plants. Nowadays, huge power generators are placed inside the dams. Water flowing through the dams spin turbine blades which are connected to generators. Power is produced and is sent to homes and businesses.

 Mostly, the fast moving water (kinetic energy) strikes the turbines and they start moving (mechanical energy) and then this energy is used to run electric generators. The transference of energy takes place from one form to another. Now instead of water wheels water falling from a vertical height is used which has stored potential energy in it due to its position and the water is then passed through the gate or vessels which take the water to the turbines which convert potential energy into mechanical energy, these vessels are called penstocks.

 The dam is made on a river to collect water. Whenever it rains, the water is collected into the dam so it serves as a water reservoir. The potential energy for further work is generated by the water level difference between the dams and the turbines because the water level in the dams is very high. Dams also control the water flow through penstocks.

 The next step is to convert this kinetic energy of water into mechanical energy. The water flows from a height throw the penstocks which are the channeled vessels to the turbines which have blades. The falling water has enough kinetic energy that when they strike hard with the blades of the turbines, they start spinning which means that the kinetic energy is converted into mechanical energy. The turbines resemble a lot with the windmills in which wind energy is used instead of water. But the turbines use potential and mechanical energy of falling water to convert into work.

 The shafts of the turbines convert the mechanical energy into electric energy. Basically, the generators work on the principle of magnets which is that when you pass a magnet near a conductor, electric current flows through it.

 The rotor having field pole rotates on a specific speed. When it rotates it passes the field poles across the stator to make sure that it has the same effect of electric field. The water should keep on moving constantly to make sure that the amount of electricity produced is great. Static water cannot generate electricity.

 The electricity via power lines is transferred to substation which provides it to the consumers.  So, the process is of great importance. It should be performed in a right manner to ensure the great production of electricity. This process is not much costly as no fuels are produced and not much health hazardous chemicals are produced by it. But the research is still going on.

 As the water flows into the reservoir from catchment area, the kinetic energy of flowing water changes to potential energy.  When the water from the reservoir falls into the intake, the gravitational potential energy stored in the water is converted into kinetic energy.  As the water flowing at a high speed strikes the blades of the turbine its kinetic energy changes to rational kinetic energy of the turbine.  As the turbine is coupled to the shaft of generator, the rotational kinetic energy of turbines changes to rotational kinetic energy of armature.  As the coils of armature rotate in magnetic field, the rotational kinetic energy of armature changes to the electric energy in its coils.

 The water required for generating Hydroelectric powers available free of cost.  Hydroelectric power stations are pollution free.  Compared to among others fossil fuels and nuclear energy, hydroelectricity is much safer. There is no fuel involved.

 For running a hydroelectric power station throughout the year, a vast amount of water is required. This demands a vast reservoir. Such a reservoir can be made only at a few places which are geographically suitable and do not interfere with eco-system and human habitation.  The minimum height required to convert the stored potential energy of water into electric energy is 34m. Between the turbine and free surface of water in reservoir. This involves massive investment on the construction of dams.

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