The energy


Energy is what the world moves. We have it when we eat, when igniting the light, when entering the Tuenti, is even necessary to think. And everything is to go and to come from Energy, that is to say, we passed it of one to another form but always it is there.

or as one is fulfilled

The energy is not only created nor is destroyed becomes€.

Without her we cannot live.

We are going to give a little time him to try to understand that it is, as is created and as we transported it.

Energy as the capacity is defined to realise changes.

Don't KnowIt goes, because we have not been a little Equal!

It is that he is a little difficult to explain although the definition is so simple, because when speaking of energy we must think that it exists in some place, if that has it he is able to use it to be able to change something.

If a car has gasoline and it uses it to move, then there is energy

If in your house you ignite the radiator and generates heat, then in the radiator there is energy

If you can read this, it means that you are alive and in you there is energy (by the way, more of the one than you imagine)

As we measured it?

This depends on that does it.

In the international system we have the basic Julio as unit and the Kj as 1000 Julios and would be the energy to raise to a meter the weight of 100 kg

If the energy is in the form of heat, we have the calorie that is equivalent to 4.18 Julio

And if it is the electricity company, we have the 3600 KWh that is equivalent to Kj

As activity we can demonstrate that 1 KWh is 3600 Kj knowing that the watt we defined it as the Julio between a second.

Problem 1. To calculate what we must pay to the electrical company to the day if we have connected a TV that consumes 0.5 amperes during 4 hours and a radiator of 10 To connected 1 hour. The price of the Kwh costs 20 pennies of Euros and the tension is 220 Volts.

Forms of energy

Chemical energy: When it exists chemical reactions between chemical components. Example: The one of combustion of the gasoline when it reacts with oxygen. If it does not have I oxygenate is no combustion. (the barbecues in the moon must hope)

hen and eggs

Thermal energy: When we passed heat of a body. A clear example is the hen that it must incubate to eggs to a constant temperature. Without the heat of the hen there is no chick.

Mechanical energy: When movement exists. A locomotive has a great amount of energy when it moves.

Nuclear energy: All that one that comes from the nucleus of atoms, either when dividing it or when uniting two to generate one the more great one.use of the reason in children

Radiating energy: Implicit in electromagnetic radiations. Examples are the light, the microwaves that emit the furnaces microwaves or the mobile phones (care with its use, because we used it next to but appraised that we have).

He is always better to use the cable of free hands that to put the mobile next to the Coco

Finally, the electrical Energy, when we have electrical charges in movement.

From where we took the energy?

If we did not consider nuclear energy,  you indirectly know some energy that does not come direct or the sun? .

We go there


1 the Aeolian one, that is taken advantage of by the wind mills (aerogenerators). It seems that nothing has to do with the sun but the wind takes place by thermal changes in the airbags, we already have to the sun

2 The one of the gas, coal, petroleum. These fuels formed by action of chemical reactions next to high pressures and long time Its origin is in the plants and the animal, that lived thanks to the sun

3 the Hydraulics is obtained when the water of the prey falls by a tube and moves a turbine. The water comes from rain, rain forms by action of the evaporation of the water thanks to the sun

There are some do not come from the sun, as nuclear energy. You know others. A track. It does not produce the sun but a friend of this one.

We can classify the Energy in Renewable (if it is not run out) and nonrenewable (if it is run out)

Examples of each are:

Energy renewable: To pave, Aeolian, Biomass, Biomass and Mareomotriz.

Nonrenewable energy: Petroleum, natural Gas, Coal and Uranium

 As It is generated, it is stored and the Electrical Energy is transported

Generally it is bad idea to store the electrical energy and when one becomes it is because it is not but remedy. The energy is in cables because the loads are moving. If it is not consumed is failed to take advantage of and the only thing that we can do is to arrange the generator (when it is possible)

We will see two cases where electrical energy is stored because it is necessary to count on her so that the control works, the lantern, the car, etc

2 horsesbattery1 by the battery that uses the cars among others.altenadorWhen its low load is used and, the alternator is in charge to provide the current for its charge it pounds2 case is Pila where load by chemical reaction of two substances and when is run out cannot be returned to load

In order to generate there is it 3 systems.

The dynamo if it is for DC and the alternator for AC voltage. The dynamo, except for use where little energy is required, is not used



In the photo superior we have a dynamo that provides current when it makes contact with the wheel


central alternator

In this case, they are connected to the axes of the turbines to generate the AC voltage.

In the image a worker carries out works of maintenance. In the hollow of the center he lacks the rotor that is the movable part of this system


In this case, the panels are in charge to provide current of direct form when light affects the same

Almost all the energy that is used in Spain takes place in power stations where the Alternator exists. This component is fundamental.

We remember that so that turns the rotor of the alternator is necessary that the turbine (that is united to the alternator) also turns. So that it turns is necessary that some fluid rotates it.

In the image of down, seen of a thermal power plant

general view of a thermal power plant

We are going to see the most important elements in this power station where a fuel is burned to generate electricity.

1 the fuel (coal, petroleum, gas. ) burning fire is introduced of the advisable way but in the boiler where and takes place heat. This heat serves to warm up the water that happens through the coil

2 When coming out of the coil (tube) the water is in the form of steam that to high pressure rotate the turbine and this one as well the rotor of the alternator

3 the alternator produces a current with a tension not very high. In order to elevate we passed it through a transformer and this one it leaves to 400,000 volts

5 the steam that leaves the turbine is gathered and happened to a condenser that transforms it of liquid steam. The condenser has a coil through which it passes cold water. The water cools the tube and this steam of the turbine. The heat is picked up by the water that when hot leaving it must cool off in the cooling tower

6 the water (already in liquid form) of the turbine happens again to the boiler to complete the cycle. (In the image it lacks a pump that pushes the water from the condenser the boiler)


The Transformer

tension transformer

It is a device that serves raisin to elevate the tension of the electrical current. It is formed by a nucleus of sweet iron and two windings.

In the image we have

N1 is the number of turns of the entrance winding

N2 is the number of turns of the exit winding

V1 is the entrance tension

V2 is the exit tension

B makes reference to the magnetic field strenght

We see as it works. When entering the current by the coil of entrance with V1 tension, that current creates a magnetic field whose lines are represented in red. The lines of field go and come by the nucleus of the transformer (in blue). The coil 2 with N2 turns picks up€ the magnetic field and it transforms it into electrical current. Since now it has but turns that pick up magnetic field€ the tension of exit are going to be greater and therefore we have increased the tension from V1 to V2.

For an ideal transformer, we do not have lost energy and therefore the Power of entrance is equal to the power output or what is the same:

P1 = P2

But as the power is the product of the tension by the intensity, we have:

V1 * I1 = V2 *I2

It is possible also to be demonstrated (as we shelp before) that the increase of tension is due to that there are but turns that take lines of field. Expressed in mathematical form

V2 = V1 *N2/N1

 But, Because we raised the tension, if at house it only arrives 220 volts to us?

tore high voltage

We must return to our formulas of electricity. We know that the cables are made of copper or aluminum. As metals that are they have resistance and the resistance causes that losses in the form of heat exist. To but resistance but lost heat in the cable and the only ones that goes away to you are useful them are the small birds that settle in them.bird on cable

We know that the Energy that is lost in a cable is

E = P/t

The power   it is V x I   and by the law of Ohm is V = I x R


The Energy is E = V x I /t = I x I x r t

that is

E = I ² x R/t

The power depends on the Intensity that circulates around the cable, therefore we must lower it to avoid that much energy by the way is lost

But we lowered and we want to maintain it the Power that is generated in the power station, That we must do?

I we return to the formula of the power, P = V x I, that is to maintain the equal P, which lowers i must raise it V

Example. If we have 1 Mw (1 million watts), if V is 1000 volts, I am 1000 Amperes, but we can raise V 100,000 and Is to 10 Amperes. We have the Mw but we have lowered the Intensity

Another reason exists, aside from the electrical one.

We know that to transport electrons it is necessary a driver. If there is to transport many electrons, a driver will make lack who allows the passage of the same, that is we must increase the section of the same (something similar to transport water). If the section is very great, the cables would consist a fortune and the towers would much more have to be resistant


In them house we normally have 220 volts in the mains. In the following table we must complete the data that lack if the network is 220 and for the hypothetical case that the network was 12 volts (as the cars). That conclusion we removed from it.

Important. In order to make these exercises we must consider that, for example, the stove must give the same heat is connected to 220 volts that to 12, therefore the energy must be the same and consequently the power in both cases is equal.

Equipment Network of 220 volts Network of 12 volts
Computer  I = 1.5 Amperes  P = I = (to consider that P is the same)
Stove I = 5 Amperes P = I =
Beater I = 2 Amperes P = I =

Nuclear power stations

Very similar to the previous ones only that the aqueous vapour is obtained in the nuclear reactor

nuclear center jet engine

nuclear fusion

To fix to you that there are many equal components.

Within the nucleus it happens the following thing.

The uranium as it is in the nature as soon as he is radioactive. Is put under it a process of enrichment€ happening to U236.

When the U236 enters the container, the neutrons bomb it, is broken in two new light nuclei but, the Krypton and the Barium

When breaking itself a great amount of energy in addition to free neutrons takes place.

The energy is taken advantage of to warm up the free water and neutrons to break new nuclei.

As we see in the image neutrons are generated but that broken nuclei. If it is not controlled is possible to be gotten to produce an excessive heating.

For it they are the control rods, made from lead, whose mission is to absorb certain amount of neutrons thus and, to control the process

The main problem of these power stations is in

a ) Where we put the radioactive residues of remainder (that by the way, nobody wants them in its house)

b ) That happens when it happens a nonpredicted event as in Japan?

In my opinion, Although the power stations are lodged in safe places and exhaustive safety measures are applied, exists a too high potential risk. The accident of Fukushima is a lesson that we must consider very.

 Hydroelectric power stations

hydroelectric power station

In this case, the changes that there are

The turbine is not of liquid water but aqueous vapour

When descending by the channel it moves the turbine and this one to the generator (alternator)

It does not exist condensing since there is aqueous vapour no

The rest is the same.

It is possible to emphasize that aside from generating clean energy, it serves to store water for the human consumption.

To see the video of unit 4

Solar power stations

We have two main types.

Photovoltaic solar power station. to pave photovoltaic


In the illustration superior are the important components but.

The solar panels composed by silicon cells, produce DC that provided to the converter, which passes the CC to AC voltage. Of there to the transformer.

In 2 Caso, we have

 Thermal solar power station.

As we see in the image, she is very similar to the thermal one, only that the elements that are in charge to warm up the water are some called mirrors heliostats that direct the sunlight to the tower where it is the coil



thermal solar power station


Parks of wind mills

air mills


 In this case we have the alternator is moved by some gears (system of gears) in charge to increase the speed of turn of the propeller shaft.

They settle in places where the conditions of winds are good (good this is evident)

The problem comes by the noise that can generate (the rubbing of the air with the shovel) but is remote of the population does not have because to be an impediment to install them

In certain occasions, the lovers of the birds have complained because they settled in the migratory routes of certain birds.

Every day they settle but with requisite air minors, since the vanes of the helices are of greater spread.

If the speed of the air increases from 10 to 20 m/s, the electrical energy does not increase of X to 2 Xs, that is it does not bend but.

We take the kinetic speed from the air as

Ec = ½ m * v ², being v the speed of the air and m the air mass


cylinderThe mass of the air we can calculate it as which it exists in the cylinder of equal area to swept by the helix and the length the outpost by the air in a second

Therefore we have:

of the density d = m/V;  m = d x V = d x (Πxr ²) x L = d x (Π x () ²) x L, where it is It the length of the vane

Now we will see Length L

In this case, we have for that second, the relation between the speed and the space comes given by

e = v/t => L = v/t = v/1 second

We are going to replace the general formula to see that we have

Ec = ½ m * v ² = ½ (d x (Π x () ²) x L) * v ² = ½ (d x (Π x () ²) x L) * v ² = ½ (d x (Π x () ²) x (v/1s)) * v ² 

Therefore we have Ec= ½ (d x (Π x () ²) x (/1s)) * v ³

If we removed all the constants outside

 Ec = ½ (d x (Π x () ²) x (v/1s)) * v ³

We arrive a


Ec = C x ² x v ³ 


where C = ½ x d x Î 

Conclusion. If the speed stops from 10 to 20, the Energy in the first case would be C X ² x 1000

For a speed of 20 we have E = C X ² 20 xs ³ = C x ² x 8000

We have increased the energy by 8

For that reason the days of wind the electrical production by wind mills increases considerably.

In order To finish this subject, to realise the Activities of Energy


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