Super conductivity is a natural phenomenon in which certain materials such as metals, alloys, and ceramics, can conduct electricity without resistance. These materials are what we call superconductors. In a superconductor, once the flow of electrons begins, it essentially goes on forever, making it an important material to humans. Superconductivity was discovered by a Dutch scientist by the name of Heike Kamerlingh Onnes in 1911. While researching properties of materials at absolute zero, this man found out that certain materials lost its resistance to the flow of electrons. For years to come, his discovery was at the head of theoretical interest. The only problem though, was that people at that time could not even think of a way to produce such a temperature, to allow materials to be superconductors at all times. This all changed in 1986 when Karl Muller and George Bednorz were working at the IBM Research Division in Zurich, Switzerland. They found a material that reached superconductivity at around 35 degrees Kelvin or –238 degrees Celsius. In the next year, a team of Chinese-American physicists declared that they had found a material that reached superconductivity at 92 degrees Kelvin. This was a big improvement. 92 degrees Kelvin is not a very high temperature, in fact, it is the equivalent of –181 degrees Celsius. Locating superconducting material above 77 degree Kelvin is a good thing because it means that the material will be easily produced and used. A theoretical understanding of superconductivity was advanced in 1957 by American physicists John Bardeen, Leon Cooper, and John Schrieffer. Their Theories of Superconductivity became know as the BCS theory (which came from each mans last name) and won them a Nobel prize in 1972. The BCS theory explained superconductivity at temperatures close to absolute zero. However, at higher temperatures and with different superconductor systems, the BCS theory has consequently became insufficient to fully explain electron behavior. The Type 1 category of superconductors is basically made up of pure metals that normally show conductivity at room temperature. They require really cold temperatures to slow down molecular vibrations enough to facilitate unrestrained electron flow in agreement to the BCS theory. BCS theory suggests that electrons team up in cooper pairs in order to help each other overcome molecular obstacles. Type 1 superconductors were discovered first and require the coldest temperatures to become superconductive. They are characterized by a very sharp transition to a superconducting state.
Dielectric study of solid polymer electrolytes is an important technique for understanding the various relaxation processes, which are associated with the ion motion. The frequency dependent dielectric constant at room temperature for the PEO with different wt% of KCl is shown in Figure 3.14(a). It is evident from the figure that the dielectric constants are significantly high in the low frequency region due to electrode polarization and space charge effects and it obeys the non-Debye type behaviour [53, 54].
William Shockley was born on February 13, 1910 in London, England. He is most famously noted for winning the Nobel Prize in physics in 1956. He won this for being the co-inventor of the transistor with John Bardeen and Walter Houser Brattain. Shockley’s parents were both Americans. His father, William Hillman Shockley, was a mining engineer born in Massachusetts. His mother, Mary Bradford, was a federal deputy surveyor of mineral lands. They returned to America when William was just a baby. They both were very encouraging for his love and passion for science, as well as his neighbor who was a professor of physics at Stanford. He got his B. Sc. Degree at the California Institute of Technology in 1932. Four years later he got his PhD from the Massachusetts Institute of Technology (MIT). He wrote his doctoral thesis on the energy band structure of sodium chloride. The title of this thesis was “Calculation of Electron Wave Functions in Sodium Chloride Crystals.”
Conducting, as we know it today is less than two centuries old.1 On the other hand time beating; a way of holding players and/or singers together, has been around for several centuries. 1 In the absence of written notation, the leader’s hands indicated the direction of the group. As polyphony entered the musical picture, it became essential that the beats be on target. Interpretation at the time was of no importance. It has been indicated through engravings that in addition to hands, leaders of instrumental and vocal forces utilized a foot, a stick, a pendulum, a handkerchief, or maybe even a piece of paper. 1 In the seventeenth century the element of interpretation entered the music scene, enhancing the role of the leader greatly. This freedom of interpretation increased the conductors responsibility, although no universal practices existed. Gradually the method of time beating approached uniformity; as meters became established, so did the conductors movements.1
The molar specific heats of most solids at room temperature and above are nearly constant, in agreement with the Law of Dulong and Petit. At lower temperatures the specific heats drop as quantum processes become significant. The Einstein-Debye model of specific heat describes the low temperature behavior.
I also decided to use a wooden block to keep hold of the wire, because
Superconductivity, a similar phenomenon, was discovered in 1911 by Dutch physicist Heike Kamerlingh Onnes. When he cooled some mercury down to liquid helium temperatures, it began to conduct electricity with no resistance at all. People began experimenting with other metals, and found that many tranisition metals exhibit this characteristic of 0 resistance if cooled sufficiently. Superconductors are analagous to superfluids in that the charges within them move somewhat like a superfluid - with no resistance through sections of extremely small cross-sectional area. Physicists soon discovered that oxides of copper and other compounds could reach even higher superconducting temperatures. Currently, the highest temperature at wich a material can be superconductive is 138K, and is held by the compound Hg0.8Tl0.2Ba2Ca2Cu3O8.33.
Distinguish between active and passive transport and define the role of each with in the mammalian kidney. Passive transport is the diffusing of molecules from areas of high concentration to low concentration across a cell membrane without the use of energy. There are four types of passive transport; Diffusion: The movement of molecules from high to low concentration. Facilitated diffusion: The movement of of molecules using carrier protein molecules to transport them across the cell membrane from high to low concentration.
of the atoms, so if there are more or larger atoms then there must be
Factors Affecting the Resistance of a Wire The aim of this experiment is to investigate one factor that affect the resistance of a wire. I will do this by performing an experiment. First I will need to identify the factors that effect resistance. There are a few factors that affect the resistance, it is determined by the properties an object has.
When we place two objects with different temperatures in contact with each other, the heat from the hotter object will immediately and automatically flow to the colder object. This is known as conduction. Some objects make excellent conductors of heat while others make poor conductors of heat or excellent insulators. Silver, copper, and gold make excellent conductors of heat. Foams and plastics make good insulators of heat but make poor conductors. Last night for dinner, I made myself a grilled cheese sandwich and a bowl of tomato soup. I heated the soup faster than I cooked the sandwich so I poured the hot soup into a bowl and finished cooking the sandwich. Once I was done cooking, I gabbed the soup bowl and burned my hand. The heat from the soup made the bowl hot. This is an example of conduction.
In some Greek experiments, objects attracted each other after rubbing. Other experiments produced objects that pushed away, or repelled, each other. The evidence showed that electric force made matter either attract or repel other matter.
People have always sought to better understand the world surrounding them through reasoning. People reason about things they wish to comprehend or things they want to question. Through reasoning, they come to a conclusion by formulating arguments supported by premises. People use arguments to convince others that their reasoning is correct. The premises may or may not effectively support the conclusion, thus this kind of faulty reasoning may be detected through correct reasoning and analyzation. There are two kinds of arguments: Inductive and Deductive arguments. Aristotle and other great thinkers believed induction and deduction were important in the explanation of the universe and scientific phenomena.
The development of superconductors has been a working progress for many years and some superconductors are already in use, but there is always room for improvement. In 1911, Dutch physicist Heike Kamerlingh Onnes first discovered superconductivity when he cooled mercury to 4 degrees K (-452.47º F / -269.15º C). At this temperature, mercury’s resistance to electricity seemed to disappear. Hence, it was necessary for Onnes to come within 4 degrees of the coldest temperature that is theoretically attainable to witness the phenomenon of superconductivity. Later, in 1933 Walter Meissner and Robert Ochsenfeld discovered that a superconducting material will repel a magnetic field. A magnet moving by a conductor induces currents in the conductor, which is the principle upon which the electric generator operates. However, in a superconductor the induced currents exactly mirror the field that would have otherwise penetrated the superconducting material - causing the magnet to be repulsed- known today as the “Meissner effect.” The Meissner effect is so strong that a magnet can actually be levitated over a superconductive material, which increases the use of superconductors. After many other superconducting elements, compounds, and theories related to superconductivity were developed or discovered a great breakthrough was made. In 1986, Alex Muller and Georg Bednorz invented a ceramic substance which superconducted at the highest temperature then known: 30 K (-243.15º C). This discovery was remarkable because ceramics are normally insulators – they do not conduct electricity well. Since their discovery the highest temperature for superconductivity to occur is 138 K (-130.15º C).
Electrical Engineers research, develop, design, and test electronic components, products, and systems for commercial, industrial, medical, military, and scientific applications (Cosgrove 749). They are concerned with devices that use small amounts of electricity that make up electronic components such as integrated circuits and microprocessors. By applying principles and techniques of electronic engineering they design, develop, and manufacture products such as computers, telephones, radios, and stereo systems (EGOE, 121). Electrical engineers touch everyone lives through the things they have designed or created. Electrical engineers have invented the lights in your house, the television, the stereo, the telephone, computers, and even your doctor’s blood pressure gauge (Stine 300).