Current electricity discovery

Italian-American physicist Nikola Tesla invents a motor that produces alternating current. This discovery changes the way electricity is transmitted over long distances. The first commercial, long-distance transmission of electricity takes place when a direct-current line provides power from Willamette Falls for street lights in Portland, Oregon. 

These studies by Volta led to the discovery of the cell which now bears his name and which, for the first time, provided a source of electricity at low voltage and moderate current. This discovery opened the way for many other investigators, who immediately capitalized on it to do a wide variety of experiments. 

Galvanic cells and batteries also played a decisive role in the development of such branches of physics as electrodynamics and electromagnetism. They were used in experiments resulting in the discovery of the well-known laws of Ampere, Ohm, Joule, Faraday and many others. The existence of galvanic cells favored practical application of electric current. Electrical telegraph and electric motors were invented and galvano-plastics was developed. 

Thermocouples Temperature measurements using thermocouples are based on the discovery by Seebeck in 1821 that an electric current flows in a continuous circuit of two different metalhc wires if the two junctions are at different temperatures. The thermocouple may be represented diagrammaticaUy as shown in Fig. 8-60. A and B are the two metals, and T and To are the temperatures of the junctions. Let T and To be the reference junction (cold junction) and the measuring junc tion, respectively. If the thermoelectric current i flows in the direc tion indicated in Fig. 8-60, metal A is customarily referred to as thermoelectricaUy positive to metal B. Metal pairs used for thermocouples include platinum-rhodium (the most popular and accurate), cmromel-alumel, copper-constantan, and iron-constantan. The thermal emf is a measure of the difference in temperature between To and T. In control systems the reference junction is usually located at... 

Some years after Davy s death, Faraday examined the corrosion of cast iron in sea water and found that it corrodes faster near the water surface than deeper down. In 1834 he discovered the quantitative connection between corrosion weight loss and electric current. With this discovery he laid the scientific foundation of electrolysis and the principles of cathodic protection. 

One of the most exciting and perhaps unexpected discoveries in science within the last decade has been the observation of superconductivity (the complete absence of resistivity to electric current) in metal oxides at temperature < 90 K. This tempera-... 

Seebeck s outstanding scientific achievement was the discovei"y of one of the three classical thermoelectric effects, which are the Seebeck, the Peltier, and the Thomson effects. Seebeck s discovery was the first, dating from 1822—1823, followed by that of Jean-Charles-Athanase Peltier in 1832 and that of William Thomson in 1854. Seebeck obseiwed that an electric current in a closed circuit comprised different metallic components if he heated the junctions of the components to different temperatures. He noted that the effect increases linearly with the applied temperature difference and that it crucially depends on the choice of materials. Seebeck tested most of the available metallic materials for thermoelectricity. His studies were further systematized by the French physicist... 

Italian physicist Allcssandro Volta creates the first continuous electrical current by making a battery out of silver and zinc strips placed in salty water. Prior to this discovery all man-made electrical sources came from static. 

German physicist George Simon Ohm publishes Die galvmische kette, mathematisch hcaihcitct, in which he describes his discovery that the voltage across an electrical conductor is proportional to the electrical current, and that the current is inversely proportional to the resistance of the conductor. 

These detectors have been important in physics virtually since the discovery of x-rays, and they gained further importance with the advent of nuclear physics. They have not as yet become important in analytical chemistry, mainly because the electric currents they generate are so minute as to make ionization detectors less convenient to use for precise measurements than others. 

II. Ease of electrical connection Here the main problem is that of efficient electrical current collection, ideally with only two electrical leads entering the reactor and without an excessive number of interconnects, as in fuel cells. This is because the competitor of an electrochemically promoted chemical reactor is not a fuel cell but a classical chemical reactor. The main breakthrough here is the recent discovery of bipolar or wireless NEMCA,8 11 i.e. electrochemical promotion induced on catalyst films deposited on a solid electrolyte but not directly connected to an electronic conductor (wire). 

The discovery of high-temperature superconductivity in mixed oxides, such as the lanthanum-barium-copper oxide complexes, has created a great deal of interest in these materials. Superconductivity, that is, the absence of any resistance to the flow of electric current, is now possible at temperatures above the temperature of liquid nitrogen (77K). Many problems remain in the development of practical processes for these materials and commercialization is not likely to occur until these problems are solved. Among the several processing techniques now used, CVD appears one of the most successful. 

The discovery of galvanic electricity (i.e. electrical phenomena connected with the passage of electric current) by L. Galvani in 1786 occurred simultaneously with his study of a bioelectrochemical phenomenon which was the response of excitable tissue to an electric impulse. E. du Bois-Reymond found in 1849 that such electrical phenomena occur at the surface of the tissue, but it was not until almost half a century later that W. Ostwald demonstrated that the site of these processes are electrochemical semipermeable membranes. In the next decade, research on semipermeable membranes progressed in two directions—in the search for models of biological membranes and in the study of actual biological membranes. 

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