18th Century Flashcards
Daniel Bernoulli Lived 1700 – 1782.
Daniel Bernoulli published his masterpiece Hydrodynamica in 1738. Bernoulli explained how the speed of a fluid affects its pressure: the Bernoulli Effect explains how an airplane’s wings generate lift.
The Kinetic Theory of Gases Bernoulli’s kinetic theory of gases. Bernoulli’s diagram from Hydrodynamica illustrating his kinetic theory of gases. The downward force from the weight is balanced by the upward force of the gas particles colliding perfectly elastically with the piston.
Early in the 1700s some scientists, led by James Hermann, had begun to believe that matter is made up of small moving particles. The more rapid the movement, the greater the temperature. This type of kinetic theory remained controversial until it was universally accepted in the 1800s.
In 1729 Euler made an attempt to explain the behavior of gases mathematically with a kinetic theory based on Robert Boyle’s gas data from 1662. Euler went wrong by assuming all the gas particles would move at the same speed. Bernoulli’s stroke of genius was to see that the particles would have a distribution of different speeds. Bernoulli’s skill in interpreting the physical world allowed him to introduce a statistical factor into kinetic theory, anticipating the work of James Clerk Maxwell over a century later.
Quote: “…the determination of the value of an item must not be based on its price, but rather on the utility it yields. The price of the item is dependent only on the thing itself and is equal for everyone; the utility, however, is dependent on the particular circumstances of the person making the estimate. Thus there is no doubt that a gain of one thousand ducats is more significant to a pauper than to a rich man though both gain the same amount.” “…in the absence of the unusual, the utility resulting from any small increase in wealth will be inversely proportionate to the quantity of goods previously possessed.”
Alessandro Volta 1745 – 1827.
Italian. Pioneer of electrical science;
• Invented the first electric battery – which people then called the “voltaic pile” – in 1800.
Using his invention, scientists were able to produce steady flows of electric current for the first time, unleashing a wave of new discoveries and technologies.
Wrote the first electromotive series; Isolated methane for the first time; discovered a methane-air mixture could be exploded using an electric spark - the basis of the internal combustion engine.
Jean Léopold Nicolas Frédéric, Baron Cuvier. 1769 – 1832 known as Georges Cuvier
French naturalist and zoologist, sometimes referred to as the “father of paleontology”.
Established the fields of comparative anatomy and paleontology through his work in comparing living animals with fossils.
Stratigraphy.
Expanded Linnaean taxonomy by grouping.
Cuvier is also known for establishing extinction as a fact—at the time, extinction was considered by many of Cuvier’s contemporaries to be merely controversial speculation. Cuvier was interpreted to have proposed that new species were created after periodic catastrophic floods.
Cuvier became the most influential proponent of catastrophism in geology in the early 19th century. Among his other accomplishments, Cuvier established that elephant-like bones found in the USA belonged to an extinct animal he later would name as a mastodon, and that a large skeleton dug up in Paraguay was of Megatherium, a giant, prehistoric ground sloth.
Suggested the earth had been dominated by reptiles, rather than mammals, in prehistoric times. Cuvier is also remembered for strongly opposing theories of evolution, which at the time (before Darwin’s theory) were mainly proposed by Jean-Baptiste de Lamarck and Geoffroy Saint-Hilaire. Cuvier believed there was no evidence for evolution, but rather evidence for cyclical creations and destructions of life forms by global extinction events such as deluges
Andres Marie Ampère 1775-1836
French Attraction without magnets!
Ampère Ampère Discovered two wires conducting current can attract or repel each other.
Volta had constructed a voltaic cell. Hans Christian Oersted had discovered electric wire could deflect compass needle: Electromagnetism.
Ampère ‘s law relates current to magnetic field density. Proposed existence of electron. Isolated fluorine.
Amedeo Avogadro Lived 1776 – 1856.
Italian Amedeo Avogadro is best known for his hypothesis that equal volumes of different I gases contain an equal number of molecules, provided they are at the same temperature and pressure. His hypothesis was rejected by other scientists. It only gained acceptance after his death. It is now called Avogadro’s law.
Avogadro was also the first scientist to realize that elements could exist in the form of molecules rather than as individual atoms. Realized that the oxygen around us exists as a molecule in which two atoms of oxygen are linked.
Avogadro’s (correct) view: the reason that two liters of hydrogen gas react with a liter of oxygen gas to form just two liters of gaseous water is that the number of particles present decreases. Therefore the chemical reaction must be: 2H2 (gas) + O2 (gas) → 2H20 (gas) In this reaction three particles (two hydrogen molecules and one oxygen molecule) come together to form two particles of water.
Avogadro’s constant is one of the most important numbers in chemistry. Its value is 6.02214129 x 10 to the 23. Avogadro did not calculate this number, but its existence follows logically from his hypothesis and work. Avogadro’s constant is the number of particles (atoms or molecules) in one mole of any substance. For example, 12 grams of carbon contains 6.02214129 x 10 to the 23 carbon atoms. Y
Carl Friedrich Gauss Lived 1777 – 1855.
Construction of the Heptadecagon
The Magnetic Field and SI Units
In 1832, with Weber’s assistance, Gauss carried out experiments whose results allowed him to define the earth’s magnetic field using units of millimeters, grams, and seconds. In other words he showed the earth’s magnetic field can be defined using purely mechanical dimensions – mass, length, and time. The work provided strong impetus for the use of SI units.
Gauss’s Law, which relates an electric field to the distribution of electric charges that cause it Gauss’s Law for Magnetism, which states that magnetic monopoles do not exist gauss’s law Gauss’s Law (for electric fields and charges) and Gauss’s Law for Magnetism. Written mathematically, these laws form two of the four equations needed to combine the electric and magnetic fields into a single, unified electromagnetic field.
Michael Faraday Lived 1791 – 1867.
British.
Bookbinder.
Assistant to Humphry Davy Royal Society at 32. Turned down the presidency.
Michael Faraday, who came from a very poor family, became one of the greatest scientists in history; remarkable in a time when science was usually the preserve of people born into wealth. T
he unit of electrical capacitance is named the farad in his honor, with the symbol F.
Devout Christian all of his life, belonging to a small branch of the religion called Sandemanians.
Michael Faraday Hits
1821: Electromagnetic Rotation Would eventually develop into the electric motor, based on Oersted’s discovery that a wire carrying electric current has magnetic properties.
1823: Gas Liquefaction and Refrigeration.
1831: Electromagnetic Induction. A varying magnetic field causes electricity to flow in an electric circuit. Enormously important. Previously, could only make current with battery. Now could move magnet to convert kinetic energy to electronic.
1834: Faraday’s Laws of Electrolysis. Vital to our understanding of batteries and electrode reactions.
1845: The Faraday Effect – a magneto-optical effect The first to link electromagnetism and light. Faraday discovered that a magnetic field causes the plane of light polarization to rotate.
Charles Lyell 1797-1875
Scottish. Lyell, following deistic traditions, favoured an indefinitely long age SSEP for the earth, despite geological evidence suggesting an old but finite age.[2]
He was a close friend of Charles Darwin. He helped to arrange the simultaneous publication in 1858 of papers by Darwin and Alfred Russel Wallace.
Lyell still struggled to reconcile his religion with natural selection.
Stratigraphy.
Uniformitarianism
From 1830 to 1833 his multi-volume Principles of Geology was published. The work’s subtitle was “An attempt to explain the former changes of the Earth’s surface by reference to causes now in operation”. He drew his explanations from field studies conducted directly before he went to work on the founding geology text.[5]
He was,an advocate of James Hutton’s idea of uniformitarianism, that the earth was shaped entirely by slow-moving forces still in operation today, acting over a very long period of time. This was in contrast to catastrophism, an idea of abrupt geological changes, which had been adapted in England to support belief in Noah’s flood.
