Thursday, 21 April 2016

WHAT ARE PUBLIC SERVICES?

Most autonomous communities are responsible for public services such as town planning and festivals.
Taxes are deducted from workers' salaries and profits that companies make. We pay an extra tax every time we buy something or use a service. This is sales tax or value added tax.
The government collects taxes. These taxes are spent on public services such as schools, hospitals, libraries, street cleaning, building roads and providing for people's pensions when they retire.

Hospitals are part of public services. Photo by Francis Tyers via wikipedia

HOW IS SPAIN ORGANISED?

Spain's 1978 Constitution established the organisation of the regions. It divided Spain's territory into 17 autonomous communities and 2 autonomous cities, Ceuta and Melilla, which are in North Africa.
There are 50 provinces.
Each autonomous community has its own Statute of Autonomy. The Statute of Autonomy defines:
  • The territory of each autonomous community.
  • The governmental institutions.
  • Its official language(s), flag, coat of arms and anthem.
An autonomous community is subdivided into:
  • A regional parliament, which has legislative powers.
  • A government, which has executive powers.
  • A Superior Court of Justice, which has judicial powers.
Photo from wikipedia.

By Emilio Gómez Fernández & Javi C. S. [GFDL (http://www.gnu.org/copyleft/fdl.html) or CC BY-SA 4.0-3.0-2.5-2.0-1.0 (http://creativecommons.org/licenses/by-sa/4.0-3.0-2.5-2.0-1.0)], via Wikimedia Commons

HOW IS POWER DISTRIBUTED IN SPAIN?

The Spanish Constitution established the basic laws of the country.
The Constitution established the division of powers: legislative, executive and judicial. each power is controlled by only one institution, so they're independent.
Legislative power is exercised by the Parliament (Cortes Generales).
Parliament makes the laws, approves the state budget and monitors the activity of the government.
It's made up of two parts: the lower house, or Congress (Congreso de los Diputados) and the upper house, or Senate (el Senado).
The Spanish Congress. Photo by Luis Javier Modino Martínez [CC BY 2.0 (http://creativecommons.org/licenses/by/2.0)], via Wikimedia Commons

The Spanish Senate. By Lcsrns (Own work) [CC BY-SA 3.0 (http://creativecommons.org/licenses/by-sa/3.0)], via Wikimedia Commons
Deputies work in Congress and Senators work in the Senate. The senators represent the autonomous communties.
Deputies and Senators are elected by citizens in general elections every four years.
Executive power is exercised by the government. The government is composed of its leader, the president, and the ministers. The ministers are responsible for specific areas such as economy, education, health or industry. The government headquarters is Moncloa Palace.
Moncloa Palace. By Flizzz http://commons.wikimedia.org/wiki/User:Flizzz [GFDL (http://www.gnu.org/copyleft/fdl.html) or CC BY-SA 4.0-3.0-2.5-2.0-1.0 (http://creativecommons.org/licenses/by-sa/4.0-3.0-2.5-2.0-1.0)], via Wikimedia Commons
Judicial power is exercised by the judicial system. It interprets the law and decides who is obeying the law or not. The judicial system imposes punishment for those who break the law. Judges work in courts and tribunals.

Thursday, 14 April 2016

HOW ARE ELECTROMAGNETS USED?

Many modern inventions use electromagnets.

ELECTRIC BELL
When the circuit is closed and the current flows through the circuit, it produces a magnetic field in the electromagnet. The hammer is attracted to the elctromagnet and hits the bell. The movement of the hammer breaks the circuit and the hammer returns to its original position. Then the cycle begins again.

MAGLEV
A magnetic levitation train uses electromagnets to levitate above its track.
The maglev has electromagnets in the base of the train.
The tracks have magnets which repel the electromagnets in the train.
The magnets above and in front of the train attract the magnets in the train, causing the train to move forward.


SPEAKERS AND MICROPHONES
Electric current travels through the coil of wire. This creates a magnetic field that switches on and off rapidly.
The magnetic field attracts the magnet, which is attached to the cone.
The cone vibrates rapidly, producing sound waves.


Wednesday, 13 April 2016

WHAT'S A DEMOCRACY?

Spain is a democracy. This means that there is freedom, justice and equality.
The United Nations Universal Declaration of Human Rights establishes fundamental human rights for all.
Eleanor Roosevelt and United Nations Universal Declaration of Human Rights in Spanish text. See page for author [Public domain], via Wikimedia Commons
So people have rights, but they also have responsibilities.
Rights in democracy (freedom to do something):
  • The right to an education.
  • The right to food and shelter.
  • The freedom to live and travel wherever we choose.
  • The freedom to express our opinions.
  • The right to associate with others.
  • The right to be treated equally by the law.
Resposibilities in democracy:
  • we must obey the law.
  • We must pay taxes to support public services.
  • We must not tolerate discrimination because of religion or race.
  • We should look after our environment.
  • We should look after people who are weaker than us.
  • We should be kind to animals.
  • Voting.

WHAT ARE THE EFFECTS OF ELECTRICITY?

THERMAL ENERGY
The electric current produces a little thermal energy as it travels through a wire, but it produces a lot of thermal energy travelling through other substances (in an oven...).
A toaster uses thermal energy from electricity. Nick carson at en.wikipedia [CC BY 3.0 (http://creativecommons.org/licenses/by/3.0)], via Wikimedia Commons
CHEMICAL REACTIONS
Electrolysis is a chemical reaction produced when an electric current flows through a liquid solution of charged particles. We us elctrolysis in electroplating: coating a metal object with a thin layer of another metal.


WHAT'S THE EARTH'S MAGNETIC FIELD LIKE?

The Earth has a magnetic field called the magnetosphere. It extends from the South Pole to the North Pole (it's as if the earth had a bar magnet in its centre). The North Pole is the South Pole of the Earth's magnetosphere.
Magnetosphere. By NASA (http://sec.gsfc.nasa.gov/popscise.jpg) [Public domain], via Wikimedia Commons
 
WHAT CAUSES THE MAGNETOSPHERE?
The centre of the Earth is made of liquid iron. This liquid moves slowly as the Earth rotates causing a magnetic field to form around the whole planet.

USING A COMPASS
A compass has a magnetised steel needle that is balanced inside a container. The north pole of the needle is painted red. It is attracted to the south pole of the magnetosphere: the magnetic north pole of the Earth. It will always point north.
Compass. By Evan-Amos (Own work) [Public domain], via Wikimedia Commons


WHY IS THE MAGNETOSPHERE IMPORTANT?
It deflects solar radiation from the Sun back into space. Radiation is harmful for plant and animal life on Earth.
It also helps us to navigate using a compass.

WHAT'S A BAR MAGNET?

Bar magnets are permanent magnets, they can't be switched on and off, they always have a magnetic field. They have two poles: north (positively charged) and south (negatively charged). They attract metals such as iron, steel, cobalt and nickel. They also attract and repel other magnets.
Bar magnet. Photo taken by Aney, 2006-03-12, GFDL via Wikimedia


WHAT DOES A MAGNETIC FIELD LOOK LIKE?
We can see the magnetic field of a bar magnet using iron filings.
By Alexander Wilmer Duff [Public domain], via Wikimedia Commons


HOW DO WE REPRESENT MAGNETIC FIELDS?
We draw lines from the north pole to the south pole of the magnet. There are more lines and they're closer together near the poles because the magnetic field is stronger there.

WHAT HAPPENS WHEN TWO MAGNETS ATTRACT OR REPEL EACH OTHER?
Look at the pictures:
Two magnets repelling. By Geek3 [GFDL (http://www.gnu.org/copyleft/fdl.html) or CC BY-SA 3.0 (http://creativecommons.org/licenses/by-sa/3.0)], via Wikimedia Commons
Two magnets attracting. By Geek3 [GFDL (http://www.gnu.org/copyleft/fdl.html) or CC BY-SA 3.0 (http://creativecommons.org/licenses/by-sa/3.0)], via Wikimedia Commons

HOW CAN WE IDENTIFY A MAGNET?
Magnets repel other magnets, but they don´t repel other substances.

Tuesday, 12 April 2016

HOW WAS ELECTROMAGNETISM DISCOVERED?

Hans Christian Oersted discovered that electric current produces a magnetic force. Oersted saw that an electric circuit switched on made the compass needle move, but he couldn't explain the phenomenon.
Picture from wikimedia

André-Marie Ampere decided to study that phenomenon. He discovered the electron, which produces both, electricity and magnetism. But he named it the 'electrodynamic molecule'. Later, other scientists named it the electron.
By Ambrose Tardieu [Public domain], via Wikimedia Commons

Michael Faraday discovered that by moving a loop of wire over a magnet, an electric current was produced in the wire. He invented the 'electromagnetic rotary device', the basis for the first electric motor or dynamo.
By Probably albumen carte-de-visite by John Watkins [Public domain], via Wikimedia Commons

Faraday Disk Generator. By Émile Alglave [Public domain], via Wikimedia Commons

SEPARATING MIXTURES WITH MAGNETS
Electromagnets are made from a wire coiled around an iron rod. The wire is connected to a power source. When the electric current flows along the wire a magnetic field is generated. When you stop the circuit, the electromagnet is switched off. Electromagnets are used in recycling plants to separate iron and steel from plastic, glass or other metals.

Homemade electromagnet. By Gina Clifford (cobalt_grrl on Flickr) [GFDL (http://www.gnu.org/copyleft/fdl.html) or CC BY-SA 4.0-3.0-2.5-2.0-1.0 (http://creativecommons.org/licenses/by-sa/4.0-3.0-2.5-2.0-1.0)], via Wikimedia Commons
Here you can see an electromagnet working: