ELECTRIC CIRCUITS AND ELECTRONICS

An electric circuit
An electric circuit is a pathway for the flow of electrons.
Electric current is a continuous flow of electron through a circuit.



Parts of an electric circuit
-Generators provide the energy that electrons need in order to move.

-Loads are devices that transform electrical energy into other types of energy that we can use.

-Switching devices are used to direct and interrupt the flow of electric current.




Diagrams and symbols



Electrical quantities
Voltage or potential difference
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 voltage, we can use a volmeter and it must be connected in parallel.

Measuring electric current
Electric current is the number of electrons that flow through the cross-section of a conductor every second. We can express this mathematically as follows: I=Q/t
Electric current is measures in amperes or amps (A) in the International System.

We can use an ammeter to measure electric current connected in series.

Electrical resistance: Ohm´s Law
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

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 the SI, this electrical energy is measured in joules (J).

ELECTRIC POWER

The electris power of a load is the amount of energy that it can transform over a certain amount of time.

If an electric current (I) flows at a particular tension (V) we can calculkate the power that is consumed: P=VxI

TYPES OF CIRCUITS
Series circuit

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

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

R=R1 + R2 + R3+ ...

 Parallel circuit

In a parallel circuit, the various components share the same input and output.

If identical batteries are connected in parallel, the voltage of the circuir will not increase. However, the total consumption of energy will be shared between the batteries, so each one will last longest.

The total resistance:1/R=1/R1+1/R2+1/R3+...

Conbination circuit

If a circuit has some elements connected in series and others elements in parallel.

Types of current
Direct current
Between the terminals of a battery, there is a continuos, stable flow of energy. If we use a voltmeter to measure the current in a car battery, the result will always be 12 volt. This is called direct current.--

Alterneting current
 Alternating current occurs when charge carriers in a conductor or semiconductor periodically reverse their direction of movement.
The variation of any electrical parameter over a period of time (in this case the electric current) is an electric signal.
The tension or voltage of domestic electricity is an alternating signal because it alternates between positive and negative values. Its waveform is also sinusoidal, with a smooth, regular shape.--


The efficiency of alterning current
The average power of alternating current is equal to the direct current that is needed to produce the same effect. In the case of an alternating sinusoidal current, the average power would be as follow: Vef = Vmax /√2 
 

Transformers
Transformers consist of two windings made of copper wire.
If we apply an alternating current to one of them (V1), it will
produce a certain voltage in the other (V2) The value will 
depend on the number of times that the copper  wire has 
been wrapped around each winding, represented as n1 and 
n2:  V1/V2 = n1/n2

CLIMATE CHANGE
Most of our electricity comes from power stations that use non-renewable energy sources, as a result, it causes an impact in the environment.

POWER STATIONS THAT USE RENEWABLE ENERGY SOURCES

There are many types of power stations that use renewable sources, such us: wind power, hydroelectric power, solar power, marine power, geothermal power and biomass powersR

HYDROELECTRIC POWER STATIONs:
-Conventional hydroelectric stations
-Pumped-storage hydroelectric stations

SOLAR POWER STATIONS
They use energy from sunlight to generate electricity. There are two types of solar power stations:

Solar thermal stations
They can use sunlight in two ways:
-With solar collectors that absorb sunlight to produce heat
-With mirrors called heliostats, that reflects and concentrate sunlight in one place.

Photovoltaic stations
Here, solar panels convert sunlight directly into electricity. Each panels contains many photovoltaic cells.

BIOMASS POWER STATIONS
Biomass is any organic material that is produced by natural processes.
In a biomass power station, the fuel used to produce energy comes from biomass. 

MARINE POWER STATIONS
They use the movement of ocean water te generate electricity. They are very expensive and not vere efficient. There are three types of marine power stations:
-Tidal power stations
-Wave power stations
-Ocean thermal conversion stations

GEOTHERMAL POWER STATIONS
They use heat from the deepest underground layers of our planet. This energy can be used in two ways:
Directly, to provide hot water for heating and industrial uses.
Indirectly: to drive generators to 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
Thermal power stations use fossil fuels to produce thermal energy. Than the thermal energy is converted to mechanical energy, in order to generate energy.

Combined-cycle power stations

A combined-cycle station is more efficient than single-cycle stations because it has two systems that produce more energy.
burns natural gas with compressed air, and the gases that it produced, they turn a turbine.
The second system uses the steam from the first system. That steam turns another turbine to produce more electricity.

NUCLEAR POWER STATIONS
A nuclear power station is a thermal power station that uses a nuclear reactor to produce heat. The reactor usesradioactive material as fuel.

ELECTRICAL ENERGY

It is a form of energy that is transported by an electrical current.

ELECTRIC POWER STATIONS
A power station is a place where energy from natural resources is transformed into energy that we can consume.

THE TRANSPORTATION AND DISTRIBUTION OF ELECTRICITY
Electrical energy must be transported from power stations to the places where it is needed. The transportation of electrical energy includes:
-Raising the voltage
-High voltage lines
-Reducing the voltage
-Final

ENERGY SOURCES

They are natural resources that we can use to generate different forms of energy. Then we can transform that energy for various purposes.

There are two types of energy sources: renewable and non-renewable.

NON-RENEWABLE ENERGY SOURCES
They come from natural resources that are limited. It would take millions of years to generate these sources of energy. The most commonly are fossil fuels and nuclear energy.

RENEWABLE ENERGY SOURCES
They comme from natural resources that we can´t set up completly. These include:

hydroelectric

solar

marine

geothermal

biomass.

ENERGY TRANSFORMATIONS

There are various types of energy transformations. We can transform chemical energy into other types of energy: 

1.Luminous energy  3.Sound energy
2.Thermal energy    4.Mechanical energyWe can transform electrical energy into:
1.Kinetic energy
2.Heat
We can transform nuclear energy into:
1.Luminous energy
2.Thermal energy
We can transform luminous energy into electrical energy.

ENERGY

Energy is the capacity of a body to perform transformations and do works.