TYPES OF CIRCUITS

SERIES CIRCUIT

Two or more elements form a series circuit when the output of one element provide the input for the next elemenat.

In the following diagram, the same current flows through all the elemnts, and the total volatge is the sum of the tensions at the end of each element

To calculate the total resistance of a circuit, we add the resistance values of each load:

                                        R=R1+R2+R3+...

One example of this type of conection would be a series of generators. The total resistance would be the sum of all the resistance values.

                                      V= V1+V2+V3+...

PARALLEL CIRCUIT

In a parallel circuit, the various components share the same input and output. In other words, the wires from both sides are joined together.

1/R=1/R1+1/R2+1/R3+...

If indetical batteries are connected in paralle, the voltage of the circuit will not increase. However, the total consumption of energy will be shared between the batteries, so each one will last longer. 

COMBINATION CIRCUIT

A combination circuit has some elements connected in series and other elements connected in parallel.

In thisa type of circuit, the current remains constant between elements that are connected in series.

At the same time, the voltage remains constant between elements that are connected in parallel

ELECTRICAL QUANTITIES

VOLTAGE OR POTENTIAL DIFFERENCE

In the circuit on the rigth, electrons flow from an electrochemical cell, though a light bulb and the back to the cell.

The amount of energy that a generator can transfer to electrons depends on its voltage (V) or electric tension. This is measured in volts (V)

If we want to measure volatage, we can use a voltmeter. This device has two wire that must be connected in parallel to the element athat we are checking.

MEASURING ELECTRIC CURRENT

Electric current (I) is the charge or nmber of electrons that flow throuht the cross-section oof a conductor every second. We can express this mathematically as follows:

                                                    I = Q/t

Electric current is measured in amperes or amps (A) in the International System or SI

ELECTRICAL RESISTANCE: OHM´S LAW

In order to measure the resistance of a lamp, the following experiment was performed with three different circuits

The resistance (R) of a material is equal to the voltage divided by the intensity of the electic current wich travels trough the material. This ratio, wich is called Ohm's Law, can be expressed as follows:
                                                  

                                                                    R=V/I

Ohm's Law has two forms:

                                                       V=RxI     and       I=V/R

The ohm (Ω) is the unit of electric resistance. The following equation can be used

                                              1Ω=1V/1A

ELECTRICAL ENERGY AND POWER

Electrical energy
If an electric current (I) flows at a particular tension (V) for a certain amount of time (t) we can calculate the energy (E) that is consumed: E=V x I x t

In this SI, this electrical energy is measured joules (J)

Electric power 

The electric power of a load is the amount of energy that it can transform over a certain amount of time.Electric power is measured in watts (W) or kilowatts (kW)

1KW/H= 3600000 j = 3600 kJ

Electric circuit and electronics

AN ELECTRIC CIRCUIT

An Electric circuit is a pathway for the flow of electrons.

Electric current is a continuous flow of electrons through a circuit

PARTS OF AN ELECTRIC CIRCUIT

Electric circuit consist of various parts:

-Generator: Cells and batteries               Loads: Light bulbs, Motirs, Resistors, Bells



Switching device: Switches, push buttons, 3-way switches

DIAGRAMS AND SYMBOLS

Environmental impact

Power stations use products that affect the environment, or example hey require the construction of new buildings and other infrastructure.

ENVIRONMENTAL IMPACT ASSESSMENT.

Any proposed new technological project include an environmental impact assessment that are all of the ecological changes that the project could cause in the local área and there also be in the economical and social repercussions of the project.

⤇Wind: It use renewable energy. It has visual and acoustic impacts and the output is low ,strong winds can cause accidents. However, wind farms are clean and help to replace our dependency on fossil fuels.




⤇Hydroelectric: It use renewable energy. It changes the flow of rivers and floods large áreas.
Hydroelectric power stations could generate disasters and dangers to plants and animals. Their output is efficient and high.




⤇Solar: It use renewable energy. These power stations take up a lot of land and installations are expensive. There are risks of burns and blindness, and their output is low. However it's clean and helps to replace our dependency on fossil fuels.



⤇Marine: It use renewable energy. The construcction of these power stations are expensive and affects the environment and the output is low. They are clean and help to replace our dependancy on fossil fuels.

⤇Biomass: It use renewable energy. Their technology is beneficial when it is used properly but it requires an excessive of natural resources. They replace our dependancy on fossil fuels and waste products that go to landfill sites.



⤇Fossil fuels: It use non-renewable energy. These power stations affects the air and the wáter and damage the environment. The pollution of the air causes respiratory ilnesses. Their output is high and efficient.

⤇Nuclear: It use non-renewable energy. They produce radioactive waste and accidents. The waste products are not reciclable. Their output is high and efficient.

Power stations that use renewable energy sources
There are some power stations that use renewable energy for reduce our dependance of fossil fuels that cause many problems in our environment. These power stations generate less energy than the others but they have many advantages:

○They produce less pollution than convetional power stations.
○They have unlimited resources.
○We dont need import so much fuels.
○They are very cheap.

WIND FARMS.

These power stations use the kinetic energy of the wind to produce energy. Wind farms work with a tower, and in the tower a turbine turns when the wind blows.
They must be installed in locations where the wind is strong. The efficiency depends on two factors:

∎The location of the power stations.
∎The number of turbines that are installed.


Wind farms are very cheap in comparaison with other power stations, and they are a totally clean source of energy. The total output of a wind farm depends on the number and size of the turbines.

HYDROELECTRIC POWER STATIONS.

These power stations use the energy of falling wáter to produce energy. Hydroelectric stations work with a recevoir, that acumulates wáter behind a high dam. The kinetic energy produced moves the blades of turbines, and the generator connected in the turbines produce energy. There are two types of hydroelectric power stations:

➝ Conventional hydroelectric power stations: The wáter flows from the recevoir trough a conduit where the wáter is in high pression. Then it flows out into a river.

➝ Pumped-storage hydroelectic stations: The wáter flows to a second recevoir. Then is pumped back to a higher recevoir. These stations are installed where there isnt enough rain to keep the upper recevoir full.



SOLAR POWER STATIONS.

These power stations use energy from rails of sun to generate energy. There are two types of solar power stations:

➦ Solar termal stations; They can use sunlight in two ways:

□ They can absorb sunlight in order to produce heat with solar collectors
□ They can reflect and concéntrate sunlight in one place with heliostats.

In both ways the water is heated to produce steam, that turns the rotor of a generator , which produces electricity.

➦ Photovoltaic stations; They work with panels ,that contains many photovoltaic cells, and covert sunlight directly into electricity. Small power installations are use for homes and rural áreas, and they are often istalled in the roof. Excess power is stored in batteries or accumulators.



BIOMASS POWER STATIONS.

Biomass is any organic thing that is produced by natural processes.
There are many types o biomass that we can use to produce energy, but in a biomass power station we use fuel produced by biomass. The steam produced from burn the biomass moves a turbine that is connected to a generator.
Some adavantages of these power stations are that they use waste materials that would normally end up in landfill sites and they produce less pollution than conventionl thermal power stations.

MARINE POWER STATIONS.

These power stations use the movement of ocean water to produce electricity. However ,they are very expensive and not very efficient. There are various types:

∎ Tidal power stations, that use the energy of tides.
∎ Wave power stations, which use the energy of waves.
∎ Ocean termal conversión stations, that use the difference in temperature between the ocean's surface and deeper áreas to produce energy.




GEOTHERMAL POWER STATIONS.

These power stations use natural heat from the Earth's surface as hot water, steam and hot gases. They can be use in two ways:

It can be used directly to provide hot water for heating and industrial uses.
 It can be used indirectly to drive generators and produce electricity.

Electric power stations that use non-renewable energy sources

There are two types: thermal power stations and nuclear power stations.

THERMAL POWER STATIONS THAT USE FOSSIL FUELS.

This type of power stations use fossil fuels for generate thermal energy, for after convert the thermal energy into mechanical energy.






Thermal power stations works with coal, oil and natural gas that heat wáter in a boiler. In the boiler turns aturbine connected to the rotor of a generator. The energy produced by the generator is transported by a network of high voltage power lines. The steam goes to a condenser, where it cools and becomes liquid wáter. Finally, the water is pumped back to the boiler.

Combined-cycle power stations.

In cogeneration power stations, electricity is generated in two systems. The first, burns natural gas with compressed air, and then it produces superheated gases, which turn a turbine to generate electricity.
The second uses the previous hot gases and uses them to produce steam in a heat recover boiler. Finally the steam turns a turbine to generate more electricity. This are the reasons because of combined-cycle stations are more efficient that the single.




NUCLEAR POWER STATIONS.

This type of power stations use nuclear reactors, that uses radioactive material (specially isotopes of uranium), to produce heat.

Nuclear power stations produce a lot of energy that we can sold at a profit, but, in these power stations happens many accidents and storage of radioactive waste.

Electrical energy

Electrical energy
It is a form of energy that is transported by an electrical current. Electricity is the most useful in the world for two reasons:

⤷It can be transformed into other types of energy so better than others.
⤷It can be transported over long distances cheapest and more efficient.

ELECTRIC POWER STATIONS.

A power station is a place when energy from natural resources is transfromed in the energy that we may use. Depends of the energy we will generate , recives a name or another.
How the electricity is generated?

If we want transform the energy into electricity, we usegenerators and if generators are used in power stations ,are called alternators. An alternator is make up by a stator and a rotor. The rotor has an even numbers of coils that receive direct current. They produce an electromagnetic field . Aturbine turns the axis of the rotor and generate electric current. This system is used at all power stations except for photovoltaic stations.


THE TRANSPORTATION AND DISTRIBUTION OF ELECTRICITY.

Power stations, usually, are place in zones far than the áreas where we use the electricity for safety reasons, for need space or for geographical features.
Electrical energy cannot be stored. There re many steps in the progress of transportation of energy:

1 Raising the voltage: the voltage is raised ,by transformers to high voltajes, because the electricity must go over large distances.

2 High voltage lines: the routes that the towers where are intalled the lines are carefully planned.

3 Reducing the voltage: The substations ,which are installed between the high voltage lines and final consumers, use Transformers to reduce the power to lower voltages.

4 Finally the power is distributed to buildings, industries and public installations. Te electric lines are installed in posts or underground. The voltage is reduced, depending on the final cosumer.

Energy sources

Energy sourcer
Energy sources are natural resources that we can use for generate different forms of energy and we can transform that energy for various purposes. We can classify into two general categories:



↠ NON-RENEWABLE ENERGY SOURCES.




They come from natural resources that are limite and can be exhausted, and it would take million years to regenerate. They are the most commonly used energy sources. They include fossil fuels and nuclear energy, which uses radioactive materials, such as uranium.









↠ RENEWABLE ENERGY SOURCES.
They come from natural resources that we cannot use up completely. They include hydroelectric, solar, marine, geotermal and biomass resources, as well as energy that we can produce from solid urban waste.

Energy transformation

Energy transformations

Everyday, we produce transformations of energy. When energy is transfomed, it may produce some unwanted forms of energy. The following examples show how:

When we rub our hands , we transformed the chemical energy in our muscles into kinetic energy, and after, the kinetic energy can be transformed into thermal energy.

The chemical energy in the fireworks is converted into light, heat , sound and mechanical energy when it explode.

The nuclear energy in stars is transformed into very intense luminous and thermal energy.

 

ENERGY

What is Energy?

Energy is the capacity of a body to perform transformations and do work. It can't be destroyed or created, it only can be transformed. Humans take their energy from food, and after we transform this energy into metabolic and muscular energy. Modern devices need electrical energy, for example; cars have motors that use gasoline or diésel as a source of energy.



➡ FORMS OF ENERGY.

In nature, these forms of energy can manifest in different ways:

POTENTIAL: Associated with the height of an object above the ground, or the storage of energy in a spring.
KINETIC: The energy of physical movement.
MECHANICAL: The sum of potential and kinetic energy.
SOUND: The energy of sound waves , which are prodced by vibrations and propagated hrough a physical médium.

ELECTRICAL: The product of an electrical current.
NUCLEAR: tThe energy in the nucleus of an atom.
LUMINOUS: Associated with light.
THERMAL OR CALORIFIC: Associated with the movment of particles in matter.
CHEMICAL: Results from the formation or descomposition of substances. For example, metabolic energy is generated by living organisms that perform chemical transformations during digestión and respiration.
ELECTROMAGNETIC: Occurs when electrical currents créate magnetic fields.

➡ UNITS OF MEASUREMENT FOR ENERGY.

Energy is measured in joules (J) , and when it takes the form of heat, we express it as calories. Relationship: 1 cal= 4.18 J.

➡ POWER.

Power is the amount of work that it can do a machine in a certain amount of time. Relationship: P=W/t. (W: work expressed in joules and t: time expressed in seconds)
In machines, the output is always less tan their energy input. This happens because some energy is always lost to friction, vibration and heat. Relationship:

Energy conversión efficiency (%)= output/input * 100