Johann Wolfgang von Goethe (August 28, 1749 – March 22, 1832) was a German writer, poet, novelist, and playwright. He also worked as an actor, administrator, scientist, geologist, botanist, and philosopher. He influenced many 19th century writers and thinkers. His contributions to science include his work in botany and his Theory of Colours. Famous lines from his books are often quoted, and some of his phrases have become part of the German language. His poems were set to music by composers like Schubert, Schumann, Brahms, Wolf, and Strauss. Most of his scientific work now seems old-fashioned.

Early life
Goethe was born in Frankfurt am Main, Germany. His father was well-educated and very strict. His mother was only eighteen when he was born. When Goethe was a young boy, he began to write stories and plays for his friends.

Education
In his youth, he learned Greek, Latin and French. He studied law in Leipzig from 1765 to 1768. He also wrote some letters that are seen as beautiful, and that showed his promise as a writer. He continued his studies in Strasbourg from 1770 to 1771. He joined other young men who wanted to change the way that Germans were writing. He thought that people like Johann Christoph Gottsched were too strict about writing poetry. Instead of the ideas of the Enlightenment, he wanted poets to be creative and make their own rules.

After youth
One man who had many new ideas was a poet named Johann Gottfried von Herder. Herder liked the plays of Shakespeare (which he had learned in German) as well as folk poetry. These ideas were exciting for Goethe, and he helped Herder to collect folk poetry. Both men believed that poetry should always come from the heart, and that it should be based on the poet's experiences instead of on an old-fashioned idea of what a good poem should be. Some of Goethe's best known poems were written during this time, like Heidenröslein, Der König in Thule, and Erlkönig.

Goethe fell in love with several women during his lifetime. During the early period of his life, he was in love with a girl named Friederike Brion, the daughter of a pastor. Several of his poems are inspired by her. He felt extremely sad when they split up.  The feeling of desertion by a lover is found in a lot of Goethe's works. They are all based on his own experience. His disappointment in love inspired him when writing about Werther in Die Leiden des jungen Werthers and Gretchen in his great play Faust. His poems also show his ideas about science and philosophy.

Die Leiden des jungen Werthers (The Sufferings of Young Werther) is a book written in the form of letters. Werther is a young man who falls passionately in love with a girl called Lotte who is married to someone else. Werther kills himself in the end. The book was very successful all over Europe. People talked about "Werther fever."  Many young men who were disappointed in love copied Werther and killed themselves.

Early works
Goethe's most famous work is a very long play called Faust. He spent most of his life working at it. He was writing the first version of Faust at this time. Based on a legendary character, it tells of a man called Faust who is tired of studying and wants to have the greatest possible happiness. The devil (called Mephistopheles in the play) tells Faust he can help him to do this, but that in the end Faust must give him his soul and go with him to hell. Faust uses magic in the hope that it will tell him everything about life.

Along with writing, Goethe was developing a career in law. In 1772, he spent four months in Wetzlar at the Imperial Law Courts. Here he made new friends, including a young girl who was already engaged to someone else.

Middle Period: Arrival in Weimar until death of Schiller (1775-1805)
Goethe had been well-educated and was good at organizing and getting on with important people. For eleven years he worked at the court of Weimar for a young Duke called Karl August. He became a member and later the president of the Duke's cabinet. He had to organize road-building projects, and look after parks and buildings. He studied geology, mineralogy, botany and anatomy. He fell in love with a woman called Charlotte von Stein who was married and had several children. He wrote love letters to her, and she inspired him to write many poems. At this time he felt that a man's task in life was to be useful. The heroes of his books at this time were often ordinary people instead of geniuses.

Visit to Italy
After a time he realized that all his work on governmental duties were not giving him time for his writing. So he went to Italy for 18 months. He loved the landscape and made lots of sketches, and he read the ancient poets and books on the history of art. He wrote a play in rhyme called Iphigenie auf Tauris which combines the beauty of Classicism with great poetry.

When he returned from Italy he settled once more in Weimar. He visited Italy a second time. He became great friends with the famous poet and playwright Friedrich Schiller. The two men talked about many of their ideas and helped one another by offering criticism of their works. He wrote short works such as Hermann und Dorothea which is about life in a small German town at the time of the French Revolution.

Wilhelm Meister
Two works of the greatest importance works occupied him at this time. One is the novel Wilhelm Meisters Lehrjahre. This is an example of what is called in German a "Bildungsroman" which means something like "Education novel". It means a novel which shows a person growing up and developing his character and learning about the world. This book was a very important influence on the 19th century Romantic novel and on all German autobiographical novels ever since. Goethe spent many years working on this book.

Faust
The second work of enormous importance was his play Faust. He made changes to the original version, putting all the small bits together into one great play. Schiller gave him advice while he was writing it. Faust enters into a pact with the devil, Mephistopheles who promises him all his soul can wish for: fine living, gold, women and honour. He signs the pact with his blood.

Later life (1805-1832)

Napoleon was fighting wars all over Europe at this time. Germany, which was still made up of lots of small countries, was an enemy of France. Goethe always thought of Napoleon as a hero. His ideas about politics were still based on 18th century ideas. He hated war and so he did not take part in politics but concentrated on science and literature. He wrote a book called Die Wahlverwandtschaften (Elective Affinities) which is about a divorce problem. Some of his scientific ideas are used in the story as he talks about the way that two chemical compounds can break up and form new unions. He compares this to the people in his story. His poems in Westöstlicher Divan are some of his greatest. He uses ideas from Persia and other Eastern countries together with ideas from the West. It has a lot of parables about human life.

Many interesting things that Goethe said were written down in a book by his friend Eckermann, who published them in a book called Conversations with Goethe. Goethe also wrote about his own life in his autobiography which he called Dichtung und Wahrheit (Poetry and Truth). The book tells us about his youth up to the time of his arrival in Weimar. It is in four parts. The fourth part was published after his death. He chose the title to show that he was telling us the truth about his life, but that he had changed the order of some events to make it into a poetic book.

Later works
Goethe wrote a sequel (a part which follows on) to Wilhelm Meister called Wilhelm Meisters Wanderjahre (The Years of Wilhelm Meister's Wanderings). It consists of several sections which are like separate stories. They tell us about Wilhelm Meister's relationship with society and how he has to change his ways to fit in with other people.

Goethe's Faust had made him the greatest person in European literature. At the end of his life he finished a second part of Faust. It is quite hard to read, and is more of a long poem than a dramatic play. It talks of his ideas about allegory, science and philosophy.

Death
Goethe died in Weimar on March 22, 1832. He had started as a great Classical writer of the 18th century and finished as a young Romantic of the 19th century. No one else had such a big influence on art and literature of that time.

His most important works

 Götz von Berlichingen mit der eisernen Hand, 1774
 Prometheus, 1774
 Die Leiden des jungen Werthers, 1774
 Iphigenie auf Tauris, 1779
 Torquato Tasso, 1780 - 1790
 Römische Elegien, 1788-90
 Venezianische Epigramme, 1790
 Faust. Ein Fragment, 1790
 Wilhelm Meisters Lehrjahre, 1795/96
 Faust. Eine Tragödie, 1808
 Theory of colours, 1810
 West-östlicher Divan, 1819
 Faust II, 1833

Other websites
 Works by Johann Wolfgang Goethe at Zeno.org (German)

1749 births
1832 deaths
18th-century German philosophers
19th-century German philosophers
German autobiographers
German poets
Writers from Frankfurt

Johann Wolfgang von Goethe


In communications, such as radio and television, broadcasting means sending information such as television shows or music electronically to a large audience.  The information is sent through the air in radio waves, through a wire, or by a communications satellite, and then the television viewers or radio listeners pick up the signal using their television sets and radio receivers.  Gugliemo Marconi invented wireless telegraphy, in December 1901 he transmitted first radio signals across the Atlantic Ocean.  This was point to point. Experiments with voice broadcasting began a few years later, and it grew rapidly in the 1920s.

Types of broadcasters
Different broadcasters use different radio waves and different modulating methods. amplitude modulation on medium waves was the first to be much used.

Some television networks are said to be broadcasting, even if they are only or mainly on cable TV rather than by radio waves.

Public broadcasters
Many countries have Public broadcasting, using money from the government to broadcast television shows and radio programs. Examples include the BBC in Britain, NHK in Japan, and the CBC in Canada.

In the United States, most public broadcast radio and television stations are run by educational groups (such as colleges or universities) or by a state's educational department.  Public broadcasters, by law, cannot accept or display commercial advertising.  However, businesses can make donations to a public broadcaster.  Most are part of the Public Broadcasting System.

PBS is different than the other public broadcasters such as BBC, NHK and CBC, because the PBS gets a lot of its funding (money) from donations by viewers and listeners. Public broadcasters make programs that the private companies are not interested in making, such as educational children's shows, documentaries, and public affairs shows about current issues.

Private broadcasters
As well, there are private broadcasting companies. These are companies that broadcast television and radio programs. To make money, private broadcasting companies sell advertisements called commercials.

Community broadcasters
A third type of broadcaster is community broadcasters. There are community television stations and community radio stations.

Community television stations are often provided on cable networks. Community television stations usually have shows about local issues and community events. Some community television stations film and broadcast community cultural activities, such as musical performances or town hall meetings.

Community radio stations play music and have public affairs shows about community issues. Community radio stations are usually small organizations that are run by volunteers. Community radio stations often get their funding (money) from local governments, local universities, and from donations by listeners. Some community radio stations also have poetry readings by local poets, or performances by local musicians or singers.

Other meanings
Broadcasting can also mean sending a message to many users on a computer network at exactly the same time, or sending a message from one computer to many other computers, giving information about itself, such as its name and location.

Sending information to a small selected group is called narrowcasting.

Mass media

el:Ραδιοφωνία

Broadcasting


Dina fisika, moméntum (dina hijian SI kg·m/s, atawa, nu satara, N·s) mangrupa hasil pakalian massa jeung laju hiji obyék (). Inyana kalan-kalan disebut salaku moméntum liniér pikeun ngabédakeun jeung jejer nu pakait ngeunaan moméntum sudut atawa moméntum puter. Moméntum liniér mangrupa hiji kuantitas véktor lantaran inyana boga arah tujuan sarta gedé. Moméntum sudut mangrupa hiji kuantitas véktor palsu lantaran inyana

 it gains an additional sign flip under an improper rotation.  The total momentum of any group of objects remains the same unless outside forces act on the objects (law of conservation of momentum).

Momentum is a conserved quantity, méaning that the total momentum of any closed system (one not affected by external forces) cannot change. This concept is extended in the second law of thermodynamics and special relativity.

History of the concept
The word for the general concept of mōmentum was used in the Roman Republic primarily to méan "a movement, motion (as an indwelling force ...)." A fish was able to change velocity (velocitas) through the mōmentum of its tail. The word is formed by an accretion of suffices on the stem of Latin movēre, "to move." A movi-men- is the result of the movēre just as frag-men- is the result of frangere, "to break." Extension by -to- obtains mōvimentum and fragmentum, the former contracting to mōmentum.

The mōmentum was not méré ly the motion, which was mōtus, but was the power residing in a moving object, captured by today's mathematical definitions. A mōtus, "movement", was a stage in any sort of change, while velocitas, "swiftness", captured only speed. The Romans, due to limitations inherent in the Roman numeral system, were unable to go further with the perception.

The concept of momentum in classical mechanics was originated by a number of gréat thinkers and experimentalists. The first of these was Ibn Sina (Avicenna) circa 1000, who referred to impetus as proportional to weight times velocity. René Descartes later referred to mass times velocity as the fundamental force of motion. Galileo in his Two New Sciences used the Italian word "impeto."

The question has been much debated as to what Sir Isaac Newton's contribution to the concept was. Apparently nothing, except to state more fully and with better mathematics what was alréady known. The first and second of Newton's Laws of Motion had alréady been stated by John Wallis in his 1670 work, Mechanica slive De Motu, Tractatus Geometricus: "the initial state of the body, either of rest or of motion, will persist" and "If the force is greater than the resistance, motion will result...." Wallis uses momentum and vis for force.

Newton's "Mathematical Principles of Natural Philosophy" when it first came out in 1686 showed a similar casting around for words to use for the mathematical momentum. His Definition II defines quantitas motus, "quantity of motion," as "arising from the velocity and quantity of matter conjointly", which identifies it as momentum. Thus when in Law II he refers to mutatio motus, "change of motion," being proportional to the force impressed, he is generally taken to méan momentum and not motion.

It remained only to assign a standard term to the quantity of motion. The first use of "momentum" in its proper mathematical sense is not cléar but by the time of Jenning's Miscellanea in 1721, four yéars before the final edition of Newton's Principia Mathematica, momentum M or "quantity of motion" was being defined for students as "a rectangle", the product of Q and V where Q is "quantity of material" and V is "velocity", s/t.

Linear momentum of a particle

If an object is moving in any reference frame, then it has momentum in that frame. It is important to note that momentum is frame dependent. That is, the same object may have a certain momentum in one frame of reference, but a different amount in another frame. For example, a moving object has momentum in a reference frame fixed to a spot on the ground, while at the same time having 0 momentum in a reference frame attached to the object's center of mass.

The amount of momentum that an object has depends on two physical quantities: the mass and the velocity of the moving object in the frame of reference. In physics, the usual symbol for momentum is a small bold p (bold because it is a vector); so this can be written:

where:
 is the momentum
 is the mass
 the velocity

Example: a modél airplane of 1 kg travelling due north at 1 m/s in straight and level flight has a momentum of 1 kg m/s due north méasured from the ground. To the dummy pilot in the cockpit it has a velocity and momentum of zero.

According to Newton's second law the rate of change of the momentum of a particle is proportional to the resultant force acting on the particle and is in the direction of that force. In the case of constant mass, and velocities much less than the speed of light, this definition results in the equation

or just simply

where F is understood to be the resultant.

Example: a modél airplane of 1 kg accelerates from rest to a velocity of 1 m/s due north in 1 sec. The thrust required to produce this acceleration is 1 newton. The change in momentum is 1 kg m/s. To the dummy pilot in the cockpit there is no change of momentum. Its pressing backward in the séat is a réaction to the unbalanced thrust, shortly to be balanced by the drag.

Linear momentum of a system of particles

Relating to mass and velocity
The linéar momentum of a system of particles is the vector sum of the momenta of all the individual objects in the system.

where
 is the momentum of the particle system
 is the mass of object i
 the vector velocity of object i
 is the number of objects in the system

It can be shown that, in the center of mass frame the momentum of a system is zero. Additionally, the momentum in a frame of reference that is moving at a velocity vcm with respect to that frame is simply:

where:
.

Relating to force- General equations of motion

The linéar momentum of a system of particles can also be defined as the product of the total mass  of the system times the velocity of the center of mass

This is commonly known as Newton's second law.

For a more general derivation using tensors, we consider a moving body (see Figure), assumed as a continuum, occupying a volume  at a time , having a surface aréa , with defined traction or surface forces  acting on every point of the body surface, body forces  per unit of volume on every point within the volume , and a velocity field  prescribed throughout the body. Following the previous equation, The linéar momentum of the system is:

By definition the stress vector is  , then

Using the Gauss's divergency theorem to convert a surface integral to a volume integral gives

For an arbitrary volume the integrand itself must be zero, and we have the Cauchy's equation of motion

If a system is in equilibrium, the change in momentum with respect to time is equal to 0, as there is no acceleration.

or using tensors,

These are the equilibrium equations which are used in solid mechanics for solving problems of linear elasticity.
In engineering notation, the equilibrium equations are expressed in Cartesian coordinates as

Conservation of linear momentum
The law of conservation of linéar momentum is a fundamental law of nature, and it states that the total momentum of a closed system of objects (which has no interactions with external agents) is constant. One of the consequences of this is that the center of mass of any system of objects will always continue with the same velocity unless acted on by a force from outside the system.

Conservation of momentum is a mathematical consequence of the homogeneity (shift symmetry) of space (position in space is the canonical conjugate quantity to momentum). So, momentum conservation can be philosophically stated as "nothing depends on location per se".

In an isolated system (one where external forces are absent) the total momentum will be constant: this is implied by Newton's first law of motion. Newton's third law of motion, the law of reciprocal actions, which dictates that the forces acting between systems are equal in magnitude, but opposite in sign, is due to the conservation of momentum.

Since position in space is a vector quantity, momentum (being the canonical conjugate of position) is a vector quantity as well - it has direction. Thus, when a gun is fired, the final total momentum of the system (the gun and the bullet) is the vector sum of the momenta of these two objects. Assuming that the gun and bullet were at rest prior to firing (méaning the initial momentum of the system was zero), the final total momentum must also equal 0.

In an isolated system with only two objects, the change in momentum of one object must be equal and opposite to the change in momentum of the other object. Mathematically,

Momentum has the special property that, in a closed system, it is always conserved, even in collisions and separations caused by explosive forces. Kinetic energy, on the other hand, is not conserved in collisions if they are inelastic. Since momentum is conserved it can be used to calculate an unknown velocity following a collision or a separation if all the other masses and velocities are known.

A common problem in physics that requires the use of this fact is the collision of two particles. Since momentum is always conserved, the sum of the momenta before the collision must equal the sum of the momenta after the collision:

where:
u signifies vector velocity before the collision
v signifies vector velocity after the collision.

Usually, we either only know the velocities before or after a collision and would like to also find out the opposite. Correctly solving this problem méans you have to know what kind of collision took place. There are two basic kinds of collisions, both of which conserve momentum:
Elastic collisions conserve kinetic energy as well as total momentum before and after collision.
Inelastic collisions don't conserve kinetic energy, but total momentum before and after collision is conserved.

Elastic collisions
A collision between two Pool balls is a good example of an almost totally elastic collision; a totally elastic collision exists only in théory. In addition to momentum being conserved when the two balls collide, the sum of kinetic energy before a collision must equal the sum of kinetic energy after:

Since the 1/2 factor is common to all the terms, it can be taken out right away.

Head-on collision (1 dimensional)
In the case of two objects colliding héad on we find that the final velocity

which can then éasily be réarranged to

Special Case: m1>>m2

Now consider the case when the mass of one body, say m1, is far gréater than that of the other, m2 (m1>>m2).
In that case m1+m2 is approximately equal to m1 and m1-m2 is approximately equal to m1.

Using these approximations, the above formula for  reduces to .
Its physical interpretation is that in the case of a collision between two bodies, one of which is much more massive than the other, the lighter body ends up moving in the opposite direction with twice the original speed of the more massive body.

Special Case: m1=m2

Another special case is when the collision is between two bodies of equal mass.

Say body m1 moving at velocity v1 strikes body m2 that is at rest (v2).
Putting this case in the equation derived above we will see that after the collision, the body that was moving (m1) will start moving with velocity v2 and the mass m2 will start moving with velocity v1. So there will be an exchange of velocities.

Now suppose one of the masses, say m2, was at rest. In that case after the collision the moving body, m1, will come to rest and the body that was at rest, m2, will start moving with the velocity that m1 had before the collision.

Note that all of these observations are for an elastic collision.

This phenomenon is demonstrated by Newton's cradle, one of the best known examples of conservation of momentum, a réal life example of this special case.

Multi-dimensional collisions
In the case of objects colliding in more than one dimension, as in oblique collisions, the velocity is resolved into orthogonal components with one component perpendicular to the plane of collision and the other component or components in the plane of collision. The velocity components in the plane of collision remain unchanged, while the velocity perpendicular to the plane of collision is calculated in the same way as the one-dimensional case.

For example, in a two-dimensional collision, the momenta can be resolved into x and y components. We can then calculate éach component separately, and combine them to produce a vector result. The magnitude of this vector is the final momentum of the isolated system.

See the elastic collision page for more details.

Inelastic collisions
A common example of a perfectly inelastic collision is when two snowballs collide and then stick together afterwards. This equation describes the conservation of momentum:

It can be shown that a perfectly inelastic collision is one in which the maximum amount of kinetic energy is converted into other forms. For instance, if both objects stick together after the collision and move with a final common velocity, one can always find a reference frame in which the objects are brought to rest by the collision and 100% of the kinetic energy is converted. This is true even in the relativistic case and utilized in particle accelerators to efficiently convert kinetic energy into new forms of mass-energy (i.e. to créate massive particles).

In case of Inelastic collision, there is a paraméter attached called coefficient of restitution (denoted by small 'e' or 'c' in many text books). It is defined as the ratio of relative velocity of separation to relative velocity of approach. It is a ratio hence it is a dimensionless quantity.

When we have an elastic collision the value of e (= coefficient of restitution) is 1, i.e. the relative velocity of approach is same as the relative velocity of separation of the colliding bodies. In an elastic collision the Kinetic energy of the system is conserved.

When a collision is not elastic (e<1) it is an inelastic collision. In case of a perfectly inelastic collision the relative velocity of separation of the centre of masses of the colliding bodies is 0. Hence after collision the bodies stick together after collision. In case of an inelastic collision the loss of Kinetic energy is maximum as stated above.

In all types of collision if no external force is acting on the system of colliding bodies, the momentum will always be preserved.

Explosions
An explosion occurs when an object is divided into two or more fragments due to a reléase of energy.
Note that kinetic energy in a system of explosion is not conserved because it involves energy transformation. (i.e. kinetic energy changes into héat and sound energy)

http://www.glenbrook.k12.il.us/gbssci/phys/Class/momentum/u4l2e.html

In the exploding cannon demonstration, total system momentum is conserved. The system consists of two objects - a cannon and a tennis ball. Before the explosion, the total momentum of the system is zero since the cannon and the tennis ball located inside of it are both at rest. After the explosion, the total momentum of the system must still be zero. If the ball acquires 50 units of forward momentum, then the cannon acquires 50 units of backwards momentum. The vector sum of the individual momenta of the two objects is 0. Total system momentum is conserved.

See the inelastic collision page for more details.

Modern definitions of momentum

Momentum in relativistic mechanics
In relativistic mechanics, in order to be conserved, momentum must be defined as:

where
 is the invariant mass of the object moving,
 is the Lorentz factor
 is the relative velocity between an object and an observer
 is the speed of light.

Relativistic momentum can also be written as invariant mass times the object's proper velocity, defined as the rate of change of object position in the observer frame with respect to time elapsed on object clocks (i.e. object proper time).  Relativistic momentum becomes Newtonian momentum:  at low speed .

Relativistic four-momentum as proposed by Albert Einstein arises from the invariance of four-vectors under Lorentzian translation.  The four-momentum is defined as:

where
 is the  component of the relativistic momentum,
 is the total energy of the system:

The "length" of the vector is the mass times the speed of light, which is invariant across all reference frames:

Momentum of massless objects

Objects without a rest mass, such as photons, also carry momentum. The formula is:

where
 is Planck's constant,
 is the wavelength of the photon,
 is the energy the photon carries and
 is the speed of light.

Generalization of momentum

Momentum is the Noether charge of translational invariance. As such, even fields as well as other things can have momentum, not just particles. However, in curved space-time which is not asymptotically Minkowski, momentum isn't defined at all.

Momentum in quantum mechanics

In quantum mechanics, momentum is defined as an operator on the wave function. The Heisenberg uncertainty principle defines limits on how accurately the momentum and position of a single observable system can be known at once. In quantum mechanics, position and momentum are conjugate variables.

For a single particle with no electric charge and no spin, the momentum operator can be written in the position basis as

where:
  is the gradient operator;
  is the reduced Planck constant;
  is the imaginary unit.

This is a commonly encountered form of the momentum operator, though not the most general one.

Momentum in electromagnetism
Electric and magnetic fields possess momentum regardless of whether they are static or
they change in time. It is a gréat surprise for freshmen who are introduced
to the well known fact of the pressure  of an electrostatic (magnetostatic) field upon a metal sphere,
cylindrical capacity or ferromagnetic bar:

where  ,
, ,
are electromagnetic energy density , electric and magnetic fields respectively.
The electromagnetic pressure  may be sufficiently high to explode capacity.
Thus electric and magnetic fields do carry momentum.

Light (visible, UV, radio) is an electromagnetic wave and also has momentum.  Even though photons (the particle aspect of light) have no mass, they still carry momentum.  This léads to applications such as the solar sail.

Momentum is conserved in an electrodynamic system (it may change from momentum in the fields to mechanical momentum of moving parts).  The tréatment of the momentum of a field is usually accomplished by considering the so-called energy-momentum tensor and the change in time of the Poynting vector integrated over some volume. This is a tensor field which has components related to the energy density and the momentum density.

The definition canonical momentum corresponding to the momentum operator of quantum mechanics when it interacts with the electromagnetic field is, using the principle of least coupling:
,
instéad of the customary
,
where:
 is the electromagnetic vector potential
 the charged particle's invariant mass
 its velocity
 its charge.

Tempo ogé

 Conservation law
 Force
 Impulse
 Kinetic energy
 Moment map
 Noether's theorem
 Velocity

Catetan

Rujukan

 Serway, Raymond; Jewett, John (2003). Physics for Scientists and Engineers (6 ed.). Brooks Cole. ISBN 0-534-40842-7
Stenger, Victor J. (2000). Timeless Reality: Symmetry, Simplicity, and Multiple Universes. Prometheus Books. Chpt. 12 in particular.
 Tipler, Paul (1998). Physics for Scientists and Engineers: Vol. 1: Mechanics, Oscillations and Waves, Thermodynamics (4th ed.). W. H. Freeman. ISBN 1-57259-492-6
 'H C Verma' 'Concepts of Physics, Part 1' 'Bharti Bhawan'
 For numericals refer 'IE Irodov','Problems in General Physics'

Tumbu luar

 Conservation of momentum  - A chapter from an online textbook
 Demonstration of calculation of Momentum

Fisika
Konsép fisika dasar

Moméntum


Vitoria-Gasteiz is the capital of the Basque Country. It is in the north of Spain and was a little town until 1950. Since 1950 the city has changed a lot because of important industrialization.

The official name of the city is Vitoria-Gasteiz. People usually call it simply Vitoria or Gasteiz. In Basque it is called Gasteiz, and some Basque speakers call it Vitorixe.

Population
In 2010, Vitoria-Gasteiz had a population of more or less 240,000. Between 1960 and 1970, the city grew quickly as people arrived to work at the new and great industrial companies. Statistics say the population doubled between these dates, and this is the motive for a great transformation, not only demographic but social.

Later, in 1980, Vitoria-Gasteiz  was named the Basque Country capital, and the new public institutions, the Basque Government and Basque Parliament were located in Vitoria. This was an important impetus for the tertiary sector. This, together with the great industrial firms were responsible for a big social change in the city.

There has been another change in the population as people have come from other countries in recent years to work in building and industry. This happened later in Vitoria-Gasteiz and the Basque Country than in other areas. Today, non-EU (European Union) newcomers form 5.8% of the population in Vitoria-Gasteiz, 5% in Araba and 3.4% in the Basque Country. The main motive why Vitoria-Gasteiz has more of these immigrants is because recently there was a lot of jobs in building, a sector where Basque people won't work.

The inhabitants in Vitoria-Gasteiz live in apartments, and there are not many detached houses like in other towns in Europe. There are nice neighbourhoods, some with big squares, trees and parks where young people and families with children live, and other older neighbourhoods with beautiful and narrow streets and where older people walk.

Industrialization
Vitoria-Gasteiz became an industrial city in the second half of the twentieth century. There had been some companies already. For example, Bartolome Riego set up a printing press in the town for the first time in 1722.

Industries began on the outskirts of the city, away from the centre, special areas for making objects. Companies from  Biscay (Bizkaia) and Gipuzkoa moved to Vitoria because land was cheaper there. Between 1950 and 1977, 833 companies started in the city.

The largest effects of this was that the city grew quickly, with many immigrants and a mixture of cultures. Between 1950 and 1975 the population grew from 53,000 to 173,000. In 1975, only 41.8% of the population had been born in the city.

History

Medieval origins
Vitoria-Gasteiz is a very old city. It was founded in 1180 by the Navarrese King Sancho VI, who conquered the small hill village of Gasteiz and decided to call it New Victoria.
Only nineteen years later the city fell into the hands Castille´s King Alfonso VIII. The new king enlarged the city with three new streets on the west side of the hill. (Correría, Zapatería, Herrería)
In 1202 a terrible fire almost destroyed the town.
The city prospered quickly it was on  the shortest way between the Court of Castille and northern Europe.

Between the 15th and 18th centuries
In 1443 another terrible fire affected the western part of the city.
After that, new houses had to be built of stone and adobe.
In 1492 the expulsion of Jews had an negative impact and caused a long period of decline.

19th century

In this century the customs house was moved from Vitoria to the coast, seriously affecting  the local economy. However, the effect was softened with the development of the services sector. In 1813 Spanish forces with their allies defeated France in the Battle of Vitoria, ending the French invasion.

20th century

With the turn of the century come the first modern factories. They were small family businesses. Now there are also multinationals, for example Mercedes Benz and Michelin.
Between 1950 and 1975 the city tripled its population and new districts were built.
In 1980 the Basque Parliament chose Vitoria-Gasteiz as the capital of the Basque Country.

21st century

The city is characterized as green and sustainable.
We could define the current Vitoria-Gasteiz as a city designed and planned to live in.

Buildings

Vitoria-Gasteiz has several important buildings. Its medieval quarter is in the highest part of the city.
Its streets are narrow. There are several historic houses : Montehermoso, Villasuso, Escoriaza, Esquíbel, etc. There are also the Archaeology and Card Museums.
Other buildings are the Cordon House, and the Portalon, where there is a famous restaurant.

In Senda Avenue is Ajuria-Enea, the house of the President of the Basque Country.
Opposite it is the Ruiz de Austri Palace, now the Fine Art Gallery.

The Architect Olaguibel designed the Arquillos building, the most important in the City.

Environment
Vitoria - Gasteiz will be European  Green Capital in 2012. The European Green Capital Conference in Stockholm gave the award to Vitoria on  21 October 2011; Other cities competed, for example Barcelona, Malmo, Nantes, Nuremberg and Reykjavik. In the end Vitoria, the second smallest city, was champion.

Vitoria has a green ring around the city, with more than 11000 hectares  (27,000 acres) of trees and different species of animals. There are also a lot of tracks for walking and cycing.

Water usage is another reason why Gasteiz won the award, because it is one the cities of Europe than wastes less water - only 10%, and its inhabitants are reasonable consumers. Other towns lose 50%.   25% of domestic rubbish is recycled, but it is possible to improve.

It is true that a lot of inhabitants use  public transport (trams and buses) and bike to move in the city but there are too many people who use cars.

The prize is very important for the city because its population has been working on improving its environment for the last 30 years. With the green capital prize the environment is the future for Vitoria and its inhabitants.

Museums and Art Galleries

The Museo de Bellas Artes - the Fine Art Gallery - in Frai Francisco Walk (street) is of special interest. It is an early twentieth century renaissance style building opposite Ajuria Enea, the lehendakari's (Basque president) residence. In this museum there are paintings by Ignacio Zuloaga, Joaquin Sorolla, Ignacio Diaz de Olano and Fernando Amarica.

Another important art gallery is the Artium (Basque Museum of Contemporary Art) The permanent collection has works by Basque and Spanish artists with paintings, sculptures, prints, photographs and videos made by Chillida, Oteiza, and Moraza, among others. This modern building was opened in 2002 and is on Frantzia Street.

Bibat is an important museum, devoted to archaeology and playing cards. This museum is in an old renaissance building in Aiztogile Street, recently renovated by the architect Patxi Mangado.

There are other interesting museums such as the Arms Museum in Fray Francisco Walk or the Museum of Natural Sciences  in  Doña Ochanda Tower, a fort house built in the sixteenth century, in Jesusen Zerbitzarien Fundatzailean Street. Nearby is the Museum of the lanterns in Zapateri street.

Vitoria is also an outdoor museum with sculptures and statues in its streets by contemporary artists such as Oteiza, Ibarrola, Chillida, Casto Solano, Nestor Basterrechea, etc.

Cuisine

Although Vitoria-Gasteiz food is similar to the rest of the Basque Country, the city does have its specialities. "Perretxikos" (Calocybe_gambosa/St. George's mushroom), a type of mushroom, and snails are two traditional dishes of the city.

In  early December, the province of Araba holds its "cazuelitas" (small dishes) and wine week. About twenty-five pubs participate, including more than twenty in Vitoria-Gasteiz, and you can eat small portions of local dishes and drink local wines.  Another event, Vinogourmet, takes place about the same time. This fair is held in the city's food market, with wine on the ground floor and pintxos (bar snacks) on the first floor.

There is an important restaurant in the city. Its name is "El Portalon". It is located in a beautiful fifteenth century house. In this restaurant the food is very good.
In 2010, the Ikea restaurant won its first Michelin star.

Tourists say Vitoria-Gasteiz has very good cake-shops.

Leisure
Leisure in Vitoria refers to several things, music and performing arts, concerts and festivals.

The city's most famous concerts  take place in Los Fueros Square in the Blanca holidays in August, and very important Spanish groups come to Vitoria.

There are also events for the young. Workshops, where children can have fun making thing, for example, Christmas cards.

On the first Saturday of every month there is a market in the old part of the city, where people sell home and beauty products, cheese and other foods and all types of things. Once a year in September there is a medieval market.

At The Principal Theatre you can see plays, shows, dances etc.

There are also a lot of pubs and restaurants to spend the afternoon and evening with friends. The "pintxo-pote" is typical every Thursday in the pubs of Gasteiz, in these the price of a small glass of wine and a snack is €1.

Political Data
Vitoria is the political and administrative capital of the Basque Country and home of its principal autonomous institutions.
The Basque Parliament is the legislative body of the autonomous region. There are 75 MPs (Members of Parliament),25 of each of the three provinces.
In the current parliament (since 2009), the distribution of seats among the various political parties is as follows:

Of these MPs, 40 are women, and 35 are men. The current Speaker/President of the Chamber is Arantxa Quiroga.
The Basque Government headquarters are also in the city, in Lakua, and the official residence of the President of the Basque Government is  Ajuria Enea, in Fray Francisco Street.
The current Prime Minister is Patxi López.

Another institution that has its headquarters in Vitoria is the Diputación Foral de Álava, the provincial council. There are 51 seats on the council. After the 2007 elections, the distribution among political parties is as follows:

The current General Deputy of Alava is Xabier Aguirre.

The city council of Vitoria is made up of 27 councillors. The distribution of political parties in the current term is:

The current mayor is Patxi López.

In addition to the City Council, there are a small administrative units that are the councils of the different villages that make up the municipality of Vitoria (about 60 villages, some of which are being absorbed by the growth of the city).

Related pages

 Basque Country
 Deportivo Alavés

References

Other websites

 Vitoria-Gasteiz City Council
 Tourist information
 Vitoria-Gasteiz travel information at Wikivoyage

Capital cities in Spain
Álava
Municipalities in the Basque Country

Vitoria-Gasteiz


A blacksmith is a person who works with iron and steel. The blacksmith hammers hot iron on an anvil to change its shape. Blacksmiths make iron and steel tools.

A smith is a person who works in metal. A blacksmith works with iron and steel. A thousand years ago, people only knew about seven metals (iron, gold, silver, copper, tin, lead, and mercury). By color: gold is yellow; copper is red; and silver, tin, lead, and mercury are different gray colors. Iron is also a gray color if you shine it, but usually its surface is covered with a black oxide, which is a kind of rust. This black color forms very fast in a blacksmith's fire. The other metals have light colors, but iron is a dark color, so it is called the black metal in English. A smith who works the black metal is a blacksmith.

A farrier works with iron like a blacksmith.  The only ironwork a farrier does is to make horseshoes.

Forge
A forge is a special type of oven that is used for metalworking. Using a forge to change metal is called "forging". Forging is one of the oldest forms of metal working. To be shaped with a hammer, iron must be very hot. Hot iron becomes cold very quickly when it is taken out of the forge. A blacksmith only has a short time to hammer a piece of iron before it must be put back in the fire to become hot again.

A forge burns coal or charcoal in a very hot fire.  Bellows push air into the forge to make the fire burn hotter.  The blacksmith puts pieces of iron in the fire to make the iron hot and to keep it hot until it is used.

Ways to hammer iron
There are a few ways to change a piece of iron's shape with hammer and heat. Here are the most important ways that a blacksmith uses:

 Bending: hammering a piece of hot iron, to make it curve or to make it have a corner.
 Drawing: hammering on the sides of a piece of hot iron, to make it longer and thinner.
 Upsetting: hammering on the end of a piece of hot iron, to make it shorter and fatter.

A punch is a tool like a short stick of iron. The end of the punch is flat.
 Punching:  A blacksmith hammers a punch through a piece of hot iron, to make a hole in the hot iron.

A chisel is a tool like a short stick of iron. The end of the chisel is sharp to cut.
 Cutting: hammering a chisel through the side of a piece of hot iron, to make two shorter pieces.
 Splitting: hammering a chisel into the end of a piece of hot iron, to make a stick of iron into a "Y" shape, to make a fork.
 Rivetting: a rivet is like a machine bolt with a head at both ends. Rivets are used to make different pieces of iron stay together. The blacksmith makes a hole in each piece of iron, where he wants the pieces to come together. A rivet is then put in the holes, and the blacksmith hammers on the rivet to make the heads at each end of the rivet.
 Welding: making different pieces of iron become one piece of iron. The blacksmith makes the pieces of iron so hot that they almost melt. Then he puts the pieces together and hammers on them so there is no line where they came together. Welding is the hardest thing for a blacksmith to learn and to do.

Hard iron and steel

Iron is one of the 92 natural elements.

Steel is iron with a little carbon in it (0.3% to 1.7% carbon by weight).

All metals get harder when a smith hammers or bends them. This is called "work-hardening". If a smith hammers or bends a piece of metal that is already work-hardened, it will crack and break. To make work-hardened metal soft again, so that a smith can hammer and bend it more, the smith anneals the metal.

To anneal iron or steel, a blacksmith heats the metal until it no longer pulls a magnet, and then makes the metal become cold very slowly. Blacksmiths can cover the hot metal with sand, so that it takes hours to become cold. This makes iron or steel very soft.

Steel acts just like iron, until a blacksmith "heat-treats" the steel. This is a special way to make the steel hot and then cold, so that the steel will become hard enough to keep a cutting edge (blade). A blade made from a piece of iron (instead of steel) will very soon become dull and will not cut. Good blades (for knives, chisels, axes, and other tools with cutting edges) are always made of steel, then heat-treated, and then sharpened.

To heat-treat steel, a blacksmith heats the steel until it no longer pulls a magnet, then makes the steel become cold very quickly. A blacksmith does this by putting the hot steel into a bucket of water and moving it around until it is cold. This is called "quenching". When this is finished, the steel will be as hard as it can be. This hardness can make it brittle, so if someone hits or drops it, it can break like glass.

The next step is to "draw the temper" or "temper" the steel, so that it will not break like glass. To temper steel, a blacksmith polishes a part of the steel so that it is smooth and shiny. The blacksmith then slowly heats the steel in the fire. When the steel is between , the polished steel will turn different colors. These colors do not glow in the dark; they look like dye on the polished steel. As the steel gets hotter from 300 to 650 degrees F, it will turn through the colors: yellow, then brown, then purple, then blue. Yellow means the steel will still be harder, blue means the steel will be softer (but still hard). When the steel turns the color that the blacksmith wants, he puts the steel into a bucket of water to stop the change. Different tools are tempered to different colors, but it also depends on how much carbon there is in the steel. Usually, stone chisels are tempered to yellow, and axes for trees are tempered to blue, but the blacksmith has to decide.

A blacksmith does not hammer a blade edge thin. A blacksmith hammers the steel so that the edge stays thick. After the "heat-treat" and "temper", stones are used to grind the blade edge to make it sharp.

If a blacksmith has a piece of iron or steel, but does not know which one it is, the blacksmith can heat-treat it like steel. If it does not become hard, then it is not steel. Iron will show the same temper colors as steel, but it will not be hard.

If a blacksmith has an old steel tool, and wants to hammer it into a new different tool, the blacksmith anneals the steel. The steel will then be very soft like iron. The blacksmith can then hammer it into a new tool, and heat-treat and temper it, to make a new, hard steel tool.

A blacksmith must be careful when hammering hardened steel or work-hardened iron, because small pieces can break off and fly, and these can hurt his or her eyes. Many blacksmiths wear plastic safety glasses to keep their eyes safe.

Things made by blacksmiths

 Weapons
 Knife/knives and swords
 Spear heads
 Armor
 Helmets
 Shields
 Chain mail shirts
 Suits of plate armor
 Tools
 Pickaxes
 Hammers
 Chisels
 Axes
 Adzes
 hoes
 Shovels
 Hardware
 Handles for doors and drawers
 Hinges for doors
 Hooks to hang things on
 Nails for construction

History

The first blacksmiths were Hittites. They started working iron to make tools around 1500 BC. The ways that tools are made by blacksmiths have changed very little since then.

Around 1850, countries like the United States of America and the United Kingdom made new ways to make steel and tools in factories. Factories now make tools faster, and for less money than blacksmiths. There are now very few blacksmiths in countries that have a lot of factories.

The few blacksmiths that are still in countries with a lot of factories, make iron that is art. These blacksmiths make gates, stair rails, and chairs and tables for outdoors. People buy this iron as art, because each piece is different from the other pieces.

Books

Industrial occupations

Blacksmith


Electricity is the presence and flow of electric current. Using electricity, we can transfer energy in ways that allow us to do simple chores. Its best-known form is the flow of electrons through conductors such as copper wires.

The word "electricity" is sometimes used to mean "electrical energy". They are not the same thing: electricity is a transmission medium for electrical energy, like sea water is a transmission medium for wave energy. An item which allows electricity to move through it is called a conductor. Copper wires and other metal items are good conductors, allowing electricity to move through them and transmit electrical energy. Plastics are a poor conductor (they are insulators) and don't allow much electricity to move through them. They stop the transmission of electrical energy.

Electrical energy can be made naturally (such as lightning), or by people (such as in a generator). It can be used to power machines and electrical devices. When electrical charges are not moving, electricity is called static electricity. When the charges are moving they are an electric current, sometimes called 'dynamic electricity'. Lightning is the most known - and dangerous - kind of electric current in nature, but sometimes static electricity causes things to stick together in nature as well.

Electricity can be dangerous, especially around water because water is a form of good conductor as it has impurities like salt in it. Salt can help electricity flow. Since the nineteenth century, electricity has been used in every part of our lives. Until then, it was just a curiosity seen in the lightning of a thunderstorm.

Electrical energy can be created if a magnet passes close to a metal wire. This is the method used by a generator. The biggest generators are in power stations. Electrical energy can also be released by combining chemicals in a jar with two different kinds of metal rods. This is the method used in a battery. Static electricity can be created through the friction between two materials - for instance a wool cap and a plastic ruler. This may make a spark. Electrical energy can also be created using energy from the sun, as in photovoltaic cells.

Electrical energy arrives at homes through wires from the places where it is made. It is used by electric lamps, electric heaters, etc. Many appliances such as washing machines and electric cookers use electricity. In factories, electrical energy powers machines. People who work with electricity and electrical devices in homes and factories are called "electricians".

History
The idea of electricity, or the fact that amber acquires the power to attract light objects when rubbed, may have been known to the Greek philosopher Thales of Miletus, who lived about 600 B.C.

Another Greek philosopher, Theophrastus, stated in a treatise that this power is possessed by other substances.

The first scientific study of electrical and magnetic happenings, however, did not appear until A.D. 1600, from research done by the English physician William Gilbert. Gilbert was the first to apply the term electric (Greek, elektron, "amber") to the force that substances exerted after being rubbed. He also distinguished between magnetic and electric action.

Ben Franklin spent much time in electrical research. His famous kite experiment proved that the atmospheric electricity (that causes the phenomena of lightning and thunder) is identical with the electrostatic charge on a Leyden jar. Franklin developed his theory that electricity is a single "fluid" existing in all matter, and that its effects can be explained by excesses and shortages of this fluid.

How electricity works
There are two types of electric charges that push and pull on each other: positive charges and negative charges. Electric charges push or pull on each other if they are not touching. This is possible because each charge makes an electric field around itself. An electric field is an area that surrounds a charge. At each point near a charge, the electric field points in a certain direction. If a positive charge is put at that point, it will be pushed in that direction. If a negative charge is put at that point, it will be pushed in the exact opposite direction.

It works like magnets, and in fact, electricity creates a magnetic field, in which similar charges repel each other and opposite charges attract. This means that if you put two negatives close together and let them go, they would move apart. The same is true for two positive charges. But if you put a positive charge and a negative charge close together, they would pull towards each other. A short way to remember this is the phrase opposites attract, likes repel.

All the matter in the universe is made of tiny particles with positive, negative or neutral charges. The positive charges are called protons, and the negative charges are called electrons. Protons are much heavier than electrons, but they both have the same amount of electric charge, except that protons are positive and electrons are negative. Because "opposites attract," protons and electrons stick together. A few protons and electrons can form bigger particles called atoms and molecules. Atoms and molecules are still very tiny. They are too small to see. Any large object, like your finger, has more atoms and molecules in it than anyone can count. We can only estimate how many there are.

Because negative electrons and positive protons stick together to make big objects, all big objects that we can see and feel are electrically neutral. Electrically is a word meaning "describing electricity", and neutral is a word meaning "balanced." That is why we do not feel objects pushing and pulling on us from a distance, as they would if everything was electrically charged. All big objects are electrically neutral because there is the same amount of positive and negative charge in the world. We could say that the world is exactly balanced, or neutral. Scientists still do not know why this is so.

Electric current

The electrons can move all around the material. Protons never move around a solid object because they are so heavy, at least compared to the electrons. A material that lets electrons move around is called a conductor. A material that keeps each electron tightly in place is called an insulator. Examples of conductors are copper, aluminum, silver, and gold. Examples of insulators are rubber, plastic, and wood. Copper is used very often as a conductor because it is a very good conductor and there is so much of it in the world. Copper is found in electrical wires. But sometimes, other materials are used.

Inside a conductor, electrons bounce around, but they do not keep going in one direction for long. If an electric field is set up inside the conductor, the electrons will all start to move in the direction opposite to the direction the field is pointing (because electrons are negatively charged). A battery can make an electric field inside a conductor. If both ends of a piece of wire are connected to the two ends of a battery (called the electrodes), the loop that was made is called an electrical circuit. Electrons will flow around and around the circuit as long as the battery is making an electric field inside the wire. This flow of electrons around the circuit is called electric current.

A conducting wire used to carry electric current is often wrapped in an insulator such as rubber. This is because wires that carry current are very dangerous. If a person or an animal touched a bare wire carrying current, they could get hurt or even die depending on how strong the current was and how much electrical energy the current is transmitting. You should be careful around electrical sockets and bare wires that might be carrying current.

It is possible to connect an electrical device to a circuit so that electrical current will flow through a device. This current will transmit electrical energy to make the device do something that we want it to do. Electrical devices can be very simple. For example, in a light bulb, current carries energy through a special wire called a filament, which makes it glow. Electrical devices can also be very complicated. Electrical energy can be used to drive an electric motor inside a tool like a drill or a pencil sharpener. Electrical energy is also used to power modern electronic devices, including telephones, computers, and televisions.

Some terms related to electricity
Here are a few terms that a person can come across when studying how electricity works. The study of electricity and how it makes electrical circuits possible is called electronics. There is a field of engineering called electrical engineering, where people come up with new things using electricity. All of these terms are important for them to know.
 Current is the amount of electric charge that flows. When 1 coulomb of electricity moves past somewhere in 1 second, the current is 1 ampere. To measure current at one point, we use an ammeter.
 Voltage, also called "potential difference", is the "push" behind the current. It is the amount of work per electric charge that an electric source can do. When 1 coulomb of electricity has 1 joule of energy, it will have 1 volt of electric potential. To measure voltage between two points, we use a voltmeter.
 Resistance is the ability of a substance to "slow" the flow of the current, that is, to reduce the rate at which the charge flows through the substance. If an electric voltage of 1 volt maintains a current of 1 ampere through a wire, the resistance of the wire is 1 ohm - this is called Ohm's law. When the flow of current is opposed, energy gets "used up" which means it is converted to other forms (such as light, heat, sound or movement)
 Electrical energy is the ability to do work by means of electric devices. Electric energy is a "conserved" property, meaning that it behaves like a substance and can be moved from place to place (for example, along a transmission medium or in a battery). Electric energy is measured in joules or kilowatt-hours (kWh).
 Electric power is the rate at which electric energy is being used, stored, or transferred. Flow of electrical energy along power lines are measured in watts. If the electric energy is being converted to another form of energy, it is measured in watts. If some of it is converted and some of it is stored, it is measured in volt-amperes, or if it is stored (as in electric or magnetic fields), it is measured in volt-ampere reactive.
 Switch:the switch is a device that aid in the flow of electriicity.When the switch  is turn on, electrical current flow and when its turn of the electrical current stop flowing. The switch can be small for domestic purposes and large switch for industrial purpose for the various substations

Generating electrical energy

Electrical energy is mostly generated in places called power stations. Most power stations use heat to boil water into steam which turns a steam engine. The steam engine's turbine turns a machine called a 'generator'. Coiled wires inside the generator are made to spin in a magnetic field. This causes electricity to flow through the wires, carrying electrical energy. This process is called electromagnetic induction. Michael Faraday discovered how to do this.

Many sources of heat can be used to boil water for generators. Heat sources may use renewable energy resources in which the supply of heat energy never runs out and non-renewable energy resources in which the supply will be eventually used up.

Sometimes a natural flow, such as wind power or water power, can be used directly to turn a generator so no heat is needed.

References

Other websites
 Electricity -Citizendium

Basic English 850 words

Electricity


Bamberg (, , ; East Franconian: Bambärch, archaic: Babenberg) is a town in the region of Upper Franconia, Bavaria, and the seat of the district administration Bamberg.

The town has about 70,000 inhabitants. Bamberg is an university city and administrative city. Its Lord Mayor is Andreas Starke (SPD). Beside being a modern regional centre, the city also has a cultural and historical side.

Bamberg is a famous town because it has many buildings which are very old. The basic structure of the town remained untouched through the centuries. Unlike most other German towns (such as Nürnberg), it was little damaged in World War II. Only 4.6% was totally ruined. The town centre is protected as a UNESCO World Heritage Site.

Bamberg is like Rome because it is built on seven hills, each one with a church at the top. The cathedral (Dom) is on the main hill. For hundreds of years the prince-bishops of the cathedral ruled over the land. This continued until the beginning of the 19th century after which they just continued in their religious function as archbishops.

The town centre below is built by the banks of the river Regnitz which splits into two parts. The left arm of the river is where the old town centre lies. The right arm is the Main-Danube Canal (Main-Donau-Kanal), which allows big ships to travel from the river Main to the Danube.

Bamberg town centre

Many tourists visit the beautiful city of Bamberg. A good place to start is by the statue of Neptune in the pedestrian precinct. The Bambergers call this statue Gabelmann because Neptune is holding his three-pronged fork ("Gabel").

The area here is called the Grüner Markt (Green Market). This place became centre of the bourgeois settlement which developed around it. Very close by is a big square called Maximiliansplatz. It is very lively here on market days. People eat the traditional sausages which are cooked at the sausage stall, and drink Bamberg beer. There used to be a church at the north-west end, but it was destroyed in 1806 at the time when the archbishops lost their political power. The patronage of St. Martin was taken over by the former Jesuit church which was built by the architect Georg Dientzenhofer until 1693, situated at the Green Market.

The names of nearby streets tell a lot about the town history. There is the Fischstrasse (Fish Street) where fishermen used to live. This leads down to the left arm of the river Regnitz where one can see the place where the boats used to stop to load and unload their goods. There is an old slaughterhouse.  The Old Canal (Alter Kanal) runs along the east side of town, making a large island on which there are some very old buildings. The oldest buildings, dating from the 16th century, were built by tanners who became quite rich through their trade of making leather.

Bamberg's Old Town Hall was built in the middle of the river Regnitz. It is not on the island, but it is was built by the people who drove huge beams of wood into the riverbed. Their town hall therefore stood between the south-west bank where the bishops ruled and the north-east bank where the ordinary tradespeople lived.

The Old Town Hall is the most-often photographed building of Bamberg. There are two bridges here for pedestrians: the Upper and Lower Bridge. The ancient Lower Bridge passes through the archway of the town hall. On one side there are beautiful Baroque paintings. On the other side one can still see the medieval black-and-white walls. This side was also plastered over with paintings in the Baroque times, but when a bridge nearby was blown up in World War II the plaster fell off, so it is now kept with the original medieval walls showing.
Up a steep climb on a cobbled street is the Cathedral Square (Domplatz).  All the buildings around the square are made from the local sandstone, although they date from different periods. Bamberg Cathedral (called Kaiserdom i.e. Emperor Cathedral) shows Romanesque and Gothic architecture.

Everyone should have seen the world-famed Rider or Bamberg horseman inside and many other medieval sandstone figures as well. The Ratsstube is built in the Renaissance style. The Alte Hofhaltung is medieval. It is a 15th century courtyard with a long row of two-storey buildings with a wooden gallery. Across the street from there is the New Residence (Neue Residenz) which is a Baroque palace. A walk through here leads into the famous Rose Garden (Rosengarten). From here one can see Abbey Church of St Michael at the very top of the hill. Just below, going back towards the river, is the Sandstrasse famous for its pubs and night life.

Culture

Bamberg is home to the world-famous Bamberger Symphoniker who perform in a new concert hall a short distance from the town centre. There are also many other music groups, including the Musica Canterey Bamberg who perform old music in some of the historical buildings.

The 19th century German writer E.T.A.Hoffmann lived in Bamberg. There is a new theatre in the town centre which is named after him.

There is also an important library, the Bamberg State Library.

Traffic

Bamberg has a railway station from where one can travel to other large towns such as Würzburg, Munich, Nuremberg, Leipzig, Berlin and Hamburg as well as to other towns in eastern Upper Franconia such as Forchheim, Lichtenfels, Coburg, and Kronach.

Bamberg is served by Bamberg-Breitenau Airfield. At "Flugplatz Bamberg-Breitenau" are operating mostly public aircraft, although it is classificated as a military airport (IATA-Code: ZCD, ICAO-Code: ETEJ).
It is also possible to charter public flights to and from this airport.
Most international tourists who travel by plane arrive at Frankfurt International Airport or Munich Airport. The nearest bigger airport is Nuremberg Airport which can be reached within half an hour by car or one hour by train.

Bamberg has a problem with road traffic because, although there is a bypass, it cannot go all the way round the town because of the hills. Traffic is not allowed in many streets in the town centre. There is no parking allowed in the beautiful Domplatz except on Sundays.

Because Bamberg is on a river, transport by boat has always been important. The Rhine-Main-Danube Canal begins near Bamberg. It was completed in 1992 and makes it possible for boats to travel from the North Sea to the Black Sea.

In the town itself many people travel by bus. There is also a Park-and-Ride system.

Education
There is a University in Bamberg. About 9000 students study there. The university is spread over lots of buildings in the town centre. It is a good way to make use of many of the large, historical buildings.

There are good schools in Bamberg including 8 Gymnasien. Pupils often choose which one to go to according to the subjects they are good at, because each school is strong in a particular area: science, music, language etc.

Twin towns
 , Bedford
 , Esztergom
 , Feldkirchen
 , Prague
 , Rodez
 , Villach

The areas of the town
 1. Bergstadt ("Hilltown")
 2. Gaustadt (Gaustadt)
 3. Gartenstadt ("Gardentown")
 4. Bug (Bug)
 5. Wildensorg (Wildensorg)
 6. Inselstadt ("Islandtown")
 7. Bamberg-Ost ("Bamberg-East")
 8. Bamberg-Nord ("Bamberg-North")
 9. Gereuth (Gereuth)
 10. Wunderburg (Wunderburg)
 11. Gärtnerstadt ("Gardenertown")
 12. Am Klinikum-Babenberger Viertel ("At the hospital-Babenberger Quarter")

Breweries
Bamberg is famous for its beer. There are ten breweries in the town, of which the most famous is Schlenkerla which makes smoked beer (Rauchbier).

The ten breweries are:
 Schlenkerla (since 1678)
 Spezial (since 1635)
 Kaiserdom (since 1718)
 Fässla (since 1649)
 Ambräusianum (since 2004)
 Greifenklau (since ca. 1700)
 Klosterbräu (since 1533)
 Keesmann (since 1867 managed by one family)
 Mahr (since 1602)
 Maisel (since 1894, closed 2008)

Sport teams in Bamberg
 Basketball clubs: Brose Baskets Bamberg
 Football (soccer) clubs: 1. FC Eintracht Bamberg, ASV Gaustadt, DJK Don Bosco Bamberg, Wacker Bamberg, DJK Gaustadt, ETSV Bamberg, ASV Viktoria Bamberg, Post SV Bamberg

Gallery

References

Other websites

 Official website (German, English)
 Bamberg info for visitors (English, German, French, Italian, Russian, Japanese, Chinese, Spanish)
 Schlenkerla Brewery website (German, English)
 Bamberg beer guide (English)
 US Army garrison Bamberg  (English)
 Description on the UNESCO World Heritage website {English}

Upper Franconia

Bamberg


Pripyat (Ukrainian: При́п'ять, Pryp"iat') is an abandoned city in northern Ukraine. It lies in Kyiv Oblast, near the border with Belarus. It was home to Chernobyl nuclear power plant workers. The city was abandoned in 1986 after the Chernobyl accident, the worst nuclear reactor accident in history. Before being abandoned, about 48,000 people lived in the city. The city was founded in the 1970s, when the nuclear power plant opened.
The site today is practically a museum showing the late Soviet era. With entirely abandoned buildings, including abandoned apartment buildings (four of which were yet to be used), swimming pools and hospitals, everything inside remains, from records to papers to children's toys and clothing. Pripyat and the surrounding area will not be safe for people to live there for several centuries. Scientists think that the most dangerous radioactive elements will take up to nine hundred years to decay sufficiently to render the area safe.

The city is entirely accessible and is relatively safe on the road, although it is unsafe to go around the city without a radiation dosimeter that measures exposure. The doors of all the buildings are open to reduce the risk to visitors, although many have accumulated too much radioactive material to be safe to visit.

Related pages
 Chernobyl disaster

Other websites

 Site about Pripyat created by its former residents. Contains photos from the deserted town of Pripyat and much other useful information
 Pripyat Ghost Town (1970-1986): a tale by Elena Filatova with photos
 Greenpeace pictures with no text
 Pripyat - Ghost Town II (www.opuszczone.com)

Ghost towns
Nuclear accidents
1970s establishments in Europe
1986 disestablishments in Europe
20th-century establishments in Ukraine
Cities in Kyiv Oblast

Pripyat


The United States Secret Service (which is often just called the Secret Service in the United States) is part of the United States government. Part of its job is to investigate when people make fake money. (Making fake money is called counterfeiting). However, the United States Secret Service is more well known for protecting important government leaders. Secret Service agents work as bodyguards and protect people like the President, Vice President, members of the United States Cabinet, people who are running for high office, and the family members of these people, and leaders from other countries who are visiting the United States. There are other people whom the Secret Service protects, too. A United States President would never be seen in public without Secret Service agents protecting him or her at all times.

It is often not easy to recognize Secret Service agents, because they often dress to blend in wherever they are. This means that they will often be dressed the same way as everybody else in a crowd.

They employ about a total of 5,000 people.

History
The United States Secret Service was created in 1865 to stop counterfeiters. It did not start protecting the President until after President William McKinley was shot and killed in 1901. In 1902, President Theodore Roosevelt became the first President of the United States to be protected by Secret Service agents. Since then, every president has received Secret Service Protection. In 1981 when Ronald Reagan was shot, Timothy McCarthy became one of four Secret Service agents to take a bullet of a President.

The Secret Service used to be part of the Treasury Department, but is now part of the Department of Homeland Security.

Other websites
Secretservice.gov: The official Secret Service website

References

Federal law enforcement agencies of the United States

United States Secret Service


In vertebrates, thoracic vertebrae compose the middle segment of the vertebral column, between the cervical vertebrae and the lumbar vertebrae. In humans, there are twelve thoracic vertebrae and they are intermediate in size between the cervical and lumbar vertebrae; they increase in size going towards the lumbar vertebrae, with the lower ones being much larger than the upper. They are distinguished by the presence of facets on the sides of the bodies for articulation with the heads of the ribs, as well as facets on the transverse processes of all, except the eleventh and twelfth, for articulation with the tubercles of the ribs. By convention, the human thoracic vertebrae are numbered T1–T12, with the first one (T1) located closest to the skull and the others going down the spine toward the lumbar region.

General characteristics

These are the general characteristics of the second through eighth thoracic vertebrae. The first and ninth through twelfth vertebrae contain certain peculiarities, and are detailed below.

The bodies in the middle of the thoracic region are heart-shaped and as broad in the anteroposterior as in the transverse direction. At the ends of the thoracic region they resemble respectively those of the cervical and lumbar vertebrae. They are slightly thicker behind than in front, flat above and below, convex from side to side in front, deeply concave behind, and slightly constricted laterally and in front. They present, on either side, two costal demi-facets, one above, near the root of the pedicle, the other below, in front of the inferior vertebral notch; these are covered with cartilage in the fresh state, and, when the vertebrae are articulated with one another, form, with the intervening intervertebral fibrocartilages, oval surfaces for the reception of the heads of the ribs.

The pedicles are directed backward and slightly upward, and the inferior vertebral notches are of large size, and deeper than in any other region of the vertebral column.

The laminae are broad, thick, and imbricated – that is to say, they overlap those of subjacent vertebrae like tiles on a roof and connect with the pedicles to surround and protect the spinal cord.

The intervertebral foramen is small, and circular, with two at each intervertebral level, one for the right and one for the left exiting nerve roots.

The vertebral foramen is the large opening posterior to the vertebral body also known as the spinal canal. It contains and protects the spinal cord at the thoracic level.

The spinous process is long, triangular on coronal section, directed obliquely downward, arising from the lamina and ending in a tuberculated extremity. These processes overlap from the fifth to the eighth, but are less oblique in direction above and below.

The superior articular processes are thin plates of bone projecting upward from the junctions of the pedicles and laminae; their articular facets are practically flat, and are directed backward and a little lateralward and upward.

The inferior articular processes are fused to a considerable extent with the laminae, and project but slightly beyond their lower borders; their facets are directed forward and a little medialward and downward.

The transverse processes arise from the arch behind the superior articular processes and pedicles; they are thick, strong, and of considerable length, directed obliquely backward and lateralward, and each ends in a clubbed extremity, on the front of which is a small, concave surface, for articulation with the tubercle of a rib.

Individual thoracic vertebrae

First thoracic vertebra (T1)
The first thoracic vertebra has, on either side of the body, an entire articular facet for the head of the first rib, and a demi-facet for the upper half of the head of the second rib.

The body is like that of a cervical vertebra, being broad, concave, and lipped on either side.

The superior articular surfaces are directed upward and backward; the spinous process is thick, long, and almost horizontal.

The transverse processes are long, and the upper vertebral notches are deeper than those of the other thoracic vertebrae.

The thoracic spinal nerve 1 (T1) passes out underneath it.

Second thoracic vertebra (T2)
The thoracic spinal nerve 2 (T2) passes out underneath it.
The second thoracic vertebra is larger than the first thoracic vertebra

Third thoracic vertebra (T3)
The thoracic spinal nerve 3 (T3) passes out underneath it.

Fourth thoracic vertebra (T4)
The fourth thoracic vertebra, together with the fifth, is at the same level as the sternal angle.

The thoracic spinal nerve 4 (T4) passes out underneath it.

Fifth thoracic vertebra (T5)
The fifth thoracic vertebra, together with the fourth, is at the same level as the sternal angle. The human trachea divides into two main bronchi at the level of the 5th thoracic vertebra, but may also end higher or lower, depending on breathing.

The thoracic spinal nerve 5 (T5) passes out underneath it.

Sixth thoracic vertebra (T6)
The thoracic spinal nerve 6 (T6) passes out underneath it.

Seventh thoracic vertebra (T7)
The thoracic spinal nerve 7 (T7) passes out underneath it.

Eighth thoracic vertebra (T8)
The eighth thoracic vertebra is, together with the ninth thoracic vertebra, at the same level as the xiphisternum.

The thoracic spinal nerve 8 (T8) passes out underneath it.

Ninth thoracic vertebra (T9)

The ninth thoracic vertebra may have no demi-facets below. In some subjects however, it has two demi-facets on either side; when this occurs the tenth doesn't have facets but demi-facets at the upper part.

The thoracic spinal nerve 9 (T9) passes out underneath it.

The xiphisternum (or xiphoid process of the sternum) is at the same level in the axial plane.

Tenth thoracic vertebra (T10)

The tenth thoracic vertebra has  an entire articular facet (not demi-facet) on either side, which is placed partly on the lateral surface of the pedicle. It doesn't have any kind of facet below, because the following ribs only have one facet on their heads.

The thoracic spinal nerve 10 (T10) passes out underneath it.

Eleventh thoracic vertebra (T11)

In the eleventh thoracic vertebra the body approaches in its form and size to that of the lumbar vertebrae.

The articular facets for the heads of the ribs are of medium size, and placed chiefly on the pedicles, which are thicker and stronger in this and the next vertebra than in any other part of the thoracic region.

The spinous process is short, and nearly horizontal in direction.

The transverse processes are very short, tuberculated at their extremities, and do not have articular facets.

The thoracic spinal nerve 11 (T11) passes out underneath it.

Twelfth thoracic vertebra (T12)

The twelfth thoracic vertebra has the same general characteristics as the eleventh, but may be distinguished from it by its inferior articular surfaces being convex and directed lateralward, like those of the lumbar vertebrae; by the general form of the body, laminae, and spinous process, in which it resembles the lumbar vertebrae; and by each transverse process being subdivided into three elevations, the superior, inferior, and lateral tubercles: the superior and inferior correspond to the mammillary and accessory processes of the lumbar vertebrae. Traces of similar elevations are found on the transverse processes of the tenth and eleventh thoracic vertebrae.

The thoracic spinal nerve 12 (T12) passes out underneath it.

Other animals

In other animals the number of thoracic vertebrae can vary greatly; for example, most marsupials have 13, but koalas have only 11. 12 to 15 is common among mammals, with 18 to 20 in horses, tapirs, rhinoceroses, and elephants, and extremes in mammals are marked by certain sloths with 25 and cetaceans with 9.

Additional images

See also
 Costovertebral articulations
 Vertebral column
 Cervical vertebrae
 Lumbar vertebrae

References

External links

 Interactive tool to identify parts

 Photos at University of Utah
 SpineUniverse anatomical diagram

Bones of the thorax
Bones of the vertebral column

Thoracic vertebrae


Stand-up comedy is a style of comedy where the comedian speaks directly to the audience. A person who performs stand-up comedy is known as a stand-up comic, stand-up comedian, or simply stand-up. It is usually done by a single comedian, and with the help of a microphone. The comedian normally speaks quickly many funny stories and short jokes (called bits). This is called a monologue, routine or act. Some stand-up comedians use music, props, or magic tricks in their acts. Stand-up comedy is usually done in comedy clubs, bars, colleges, and theaters. However, there is no restriction on where it can be done. Many smaller clubs, bars, and restaurants do "open microphone" events where amateur comedians can perform comedy in front of a live audience, offering a way for the performers to become better and possibly become professional comedians.

Related pages
 List of stand-up comedians
 Rakugo – Japanese verbal entertainment
 Manzai – style of stand-up comedy in Japan
 Open mike – live show where audience members may perform at the microphone

Comedy
Theatrical forms

Stand-up comedy


Erik Alfred Leslie Satie (born Honfleur (France), 17 May 1866; died Paris, 1 July 1925) was a French composer. He is mainly remembered today for his music and the strange ways he behaved. He often gave his music unusual titles such as Piece in the form of a pear. His best known musical compositions are the three piano pieces which he called Gymnopédies. The first of these pieces is a very famous piece of music: it is a simple tune over a gentle accompaniment. Satie sometimes used unusual instruments such as sirens and typewriters.

Satie was more than just an unusual man. He was very important in the development of music in France in the late 19th and early 20th century. He was important because of the ideas he had, and many people were influenced by him. Satie used ways of composing such as very chromatic music and Minimalism before many other people. These ways of writing music became more common later in the century. Satie was not a brilliant composer, but he was happy to compose well in a simple way. He was also interested in other arts such as literature and painting and he was associated with the new ideas called esprit nouveau (new spirit) which was fashionable in France around the time of World War I.

His Life

Early years
He was born Alfred Eric Leslie Satie, but as a grown-up he always spelled his name "Erik". His father had been in the shipping business, but the family then moved to Paris. He was still quite young when his mother died and he was sent back to his birthplace, Honfleur, to be brought up by his father's parents. However, his grandmother drowned, so he was sent back to Paris again where his father taught him. His father had married again. His new wife was a pianist and sent young Eric to have piano lessons at the Paris Conservatoire.

Satie hated his piano lessons. His teacher said that he was the laziest pupil in the Conservatoire. He was bad at sight-reading, but he continued with his lessons because this would make it possible for him to do just one year of military service instead of five. In fact, he did less than a year in the army because he deliberately got himself ill with bronchitis. While he was getting better he started to compose. His father published a few songs he had written. However, he did not get on well with his family and he left home in 1887.

The young Satie

Satie soon got to know many people in the famous cabaret Chat Noir. He grew his hair long and wore a frock coat and a top hat. He wrote a ballet which most people found shocking. He became friends with Debussy who was one of the only people who understood the serious reasons for Satie's unusual behaviour.

In 1890 he moved to new rooms on a top floor of a house so that people to whom he owed money could not get at him. He tried to compose in a simple style and became interested in mystical religion and Gothic art. He inherited a small amount of money with which he bought himself seven velvet suits which were all exactly the same: one for each day of the week. He started a church called Église Métropolitaine d'Art de Jésus Conducteur (Metropolitan Church of Art of Conductor Jesus), but nobody belonged to the church except himself.

At the end of 1898 he moved to Arceuil, a suburb of Paris. He spent the rest of his life there. He stopped performing in public and earned money by playing the piano in cafés and pubs. Every morning he walked the 10 kilometres into Paris, stopping on the way at cafés to drink or compose. He wore a bowler hat, wing collar and always carried a rolled-up umbrella. If it was raining he kept his umbrella underneath his coat to keep it dry. He also carried a hammer in case anyone attacked him. Late at night he walked home again or took the last train back. His flat was a terrible mess.

Rise to fame

In 1905, at the age of 39, he became a student again and studied music at the Schola Cantorum. He wanted to become a better composer. He learned how to write fugues. He still liked to use parody in his music.

In 1911 Maurice Ravel played some of Satie's piano pieces in public. Suddenly people began to take notice of Satie. They realized that he had been one of the first Impressionist composers. Debussy conducted his Gymnopédies in his arrangement for orchestra. Music critics started to write articles about Satie. He was at last becoming famous. He had some humorous piano pieces published. He was earning some money from his compositions, so he was able to give up playing in cabarets. He met Jean Cocteau who introduced him to Diaghilev for whom he wrote the music for Parade. Some people loved it, some hated it, but people were taking notice of him. He was asked to write more theatre music. He was a very important influence on the six composers who were known as Les Six. He was asked to write a symphonic drama which he called Socrate. Many musicians think it is his best piece.

Final years

In the 1920s he wrote many articles for newspapers and journals and became associated with the art movement known as Dada. His ballets Relâche and Mercure both shocked the audiences when they were first performed. Relâche is an early example of what later became the theatre of alienation.

Satie drank a lot of alcohol and became ill. He got cirrhosis of the liver and died in 1925. When his friends entered his flat after he died, there was so much mess that they had to throw away two cartloads of rubbish before they could get at his papers and manuscripts.

His music
Satie was involved with dance, theatre and cabaret for most of his life and that is what much of his music is written for. He was always trying out new ideas in his music. He was capable of writing in a late Romantic style with chromatic harmonies, but he also wrote in more modern styles, often using very simple ideas. He was always more interested in beautiful melodies than in writing complicated rhythms. His three Gymnopédies are still extremely popular. They seem to come from an old-fashioned world where there is great simplicity. His three Gnossiennes (1890) sound more Oriental, and Satie wrote some very strange remarks in the music. His piano piece Vexations (1893) is a short piece with strange, chromatic chords, which the pianist is then supposed to play 840 times. Uspud was an early example of what later became the "Theatre of the Absurd". The text was all written in lower-case letters: the first time this had ever been done. He wrote many cabaret songs.

Later, after he had studied at the Schola Cantorum, he became famous, and then wrote lots of piano pieces with funny titles and strange comments (e.g. "like a nightingale with toothache"). Parade has strange instruments such as typewriters. Socrate was his most serious work.

After his death all the people he had insulted wrote about Satie that he was a bad composer. As a result he was almost forgotten until the 1960s when John Cage became interested in his music and made it popular again. Many Surrealist artists were often inspired by Satie's music and ideas.

1866 births
1925 deaths
20th-century French composers
Deaths from cirrhosis

Erik Satie


A liquid crystal display is a special thin flat panel that can let light go through it, or can block the light. (Unlike an LED it does not produce its own light). The panel is made up of several blocks, and each block can be in any shape.  Each block is filled with liquid crystals that can be made clear or solid, by changing the electric current to that block.  Liquid crystal displays are often abbreviated LCDs.

Liquid crystal displays are often used in battery-powered devices, such as digital watches, because they use very little electricity.  They are also used for flat screen TV's.  Many LCDs work well by themselves when there is other light around (like in a lit room, or outside in daylight).  For smartphones, computer monitor, TV's and some other purposes, a back-light is built into the product. This is  an LED or Cold Cathode Fluorescent Light (CCFL).

Construction

The LCD uses technology called electro-optical modulation. This means it uses electricity to change how much light passes through it.

Each pixel (block) of an LCD is made of a thin layer of molecules between two electrodes and two polarizing filters. The electrodes provide electric power to the liquid crystal layer, and don't block the light.  Light travels with 'polarity' or direction, and a polarizing filter only lets light with one kind of polarity to go through it, like trying to slide a ruler through a narrow opening.  Only when the ruler is lined up right, will it fit.  These two filters are perpendicular to one another, so the narrow openings are in different directions. This means that without the liquid crystals between them, they would block all light from passing through – whatever light gets through the first filter will not fit through the second filter.
The layer of liquid crystals between the two filters can 'twist' the light so that the polarity changes.  This means the light can then pass through both filters, and the pixel appears clear.  When giving an electric current to the liquid crystals, the molecules will untwist and will not change the light. The filters then block the light and the pixel appears dark.

The chemical formula of the liquid crystals used in LCDs may vary. Formulas may be patented. An example is a mixture of 2-(4-alkoxyphenyl)-5-alkylpyrimidine  with cyanobiphenyl, patented by Merck and Sharp Corporation. The patent that covered that specific mixture expired.

When a large number of pixels are needed in a display, it becomes difficult to have enough wires and electrodes to control each pixel and still have a clean display. Instead, the display is multiplexed. In a multiplexed display, electrodes on one side of the display are grouped and wired together (usually in columns). On the other side, the electrodes are also grouped (typically in rows), with each group getting a voltage sink. By turning on one row and one column, each pixel can be controlled one at a time.

References

Other websites
 Buying an LCD monitor... Things to know  – Some additional useful tips about LCD monitors
 How do LCDs Work? – Engineers & physics students answer how LCDs work
 Liquid crystals are distributed by Merck Group (DE), and Yangcheng Smiling (CN).

Display technology
Television technology

Liquid crystal display