Into the magnetic world-留学Essay代写－r51due

英国essay论文精选范文：“Into the magnetic world”，这篇论文讨论了磁的世界。我们生活在一个磁的世界，无时无刻不受到地球磁场的呵护，无论何时何地都在与磁打交道，从普通电话机到电冰箱、电磁炉，从车票到银行卡，从发电机到磁悬浮列车。说到磁，不能不说磁的任性。众人皆知，每一个磁体都有N极和S极。如果把一个完整的磁体切成两部分，那么每个部分的磁体又都有N极和S极，再切下去还是如此。总之，磁体即使粉身碎骨也不会改变初衷，仍坚守自己的N极和S极。

Ancient people not only understand the nature of a magnet attracts iron, and later with magnet to find iron ore was known. The so-called "iron CI Shi Zhao", in fact, is the process of iron is magnetic. Magnetic susceptibility is obtained which no magnetic material magnetic processes. In addition to the iron, steel, nickel, cobalt and a few materials, most other materials cannot be magnetized, so, iron, steel, nickel, cobalt and other materials that can be magnetized is called a ferromagnetic material, others say non-ferromagnetic materials.

The internal causes of ferromagnetic material is magnetized, ferromagnetic materials are made is called "domain" consists of magnetic community, and each domain is equivalent to a small magnet. In the case of no external magnetic field, the smaller magnetic domains are arranged in haphazard, offset with each other and external magnetic. Once under external magnetic field, the magnetic domains along the direction of the magnetic field alignment, creating additional magnetic field and the magnetic field increased.

When it comes to magnetic, magnetic wayward say. Everyone knows, every n pole and s pole of the magnet. If you complete a magnet into two parts, each part of the n pole and s pole of the magnet, and then cut or so. All in all, magnets even if the pieces will not change their minds, still firmly in its n pole and s pole.

However, it was in the analogy of magnetism and electricity, made a wild guess: positive and negative charges can stand alone, then for the magnets should only take n or s pole of the magnetic monopole existed. In 1932, the United Kingdom physicist Dirac Monopole is extrapolation can exist independently. Dirac this prediction has attracted the interest of many physicists, and using a variety of methods to search for magnetic monopoles. The view was expressed that, at the beginning of the universe has created a lot of magnetic monopoles. However, until now scientists had not found evidence of magnetic monopoles exist. Maybe magnetic monopoles do not exist at all, maybe on the secrets of magnetic have a lot has not been cracked.

With the magnetic phenomenon and electrical phenomenon in both awareness of the enormous forces gradually, people have begun to consider the magnetic and electric phenomena are inherently linked. In 1820, Denmark scientists Oster made an important discovery, that power has a magnetic field around the wire, and the deflection of the compass needle near the leads. This phenomenon is called the magnetic effects of electric current. Meanwhile, current direction changed, deflected a magnetic needle direction also changes. This gave United Kingdom physicist Michael Faraday to enlightenment, he decided to search for magneto-electric method, and finally in one day in October 1831, he insulation sheath of copper thin wire with masses of paper wrapped around a cylinder and copper on both ends of the wire is connected to a galvanometer. When he when the magnets into a cylindrical paper tubes, galvanometer pointer suddenly turned up, this is the phenomenon of electromagnetic induction. Faraday concluded the law of electromagnetic induction, invented the first generation in the history of electromagnetism and the motor.

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Generator is a device that converts the mechanical energy into electrical energy, which is mainly formed by rotating armature and magnet system, its principle of operation is the armature coil in a magnetic field rotates cut magnetic lines on induced electromotive force and current, so it can be external power. While the motor is a type of devices convert electrical energy into mechanical energy, which is under the magnet and coil around armature consisting of, but when working with the motor armature current in the coil is supplied by external power supply. Generators and Motors at work is inseparable from the magnet, magnets in electromagnetic energy conversion has played an important role in the process. Transformers of widely used in life, when their work is inseparable from the magnet. Visible, magnets and magnetic phenomena found on electric propulsion and had an important impact on the lives of mankind.

In modern life, tiny magnetic card can be seen everywhere, enjoy the card brings us when it is convenient and fast, a lot of people may not know the working principle of magnetic cards.

Card is a typical example of using magnetic, it is made up of base material and coating evenly on top of the base made of magnetic particles. How magnetic materials recorded information on the card do?

Write or read information to the card, require special technical devices to be completed. Like to write some data and information on the card, as long as the card on the magnetic surface moving at a certain speed, or there are gaps in the torus and wound around an iron core coils work on moving heads, magnetic surface on the card will contact with the recording head gaps. When the head after applying a current in the coil, the gaps will produce a current proportional to the magnetic field, magnetic contact with void part of the magnet is magnetized. Magnetic cards of the gap left by the magnetosphere leaving remanence of the corresponding to the current changes, it means information is recorded on a magnetic card in the form of residual magnetism on the storage card. While reading the information on the card, as long as the cards placed on the head to move, can be transferred and read magnetic cards on the signal.

Magnetic cards are some of the different physical structures and data structures, such as common bank card on the tapes with 3 tracks, and each track record with different information. Bank systems, security systems, identification systems, driver's license management system, typically on 3 tracks on the card format requirements of different applications. Each track is substantially the same as the width of about 2.8 mm, mainly for the storage of user data; next to about 0.05 mm of clearance between the two tracks, mainly used to differentiate between the two tracks. Because of the magnetic card is low cost, easy to use, easy to manage, and high security features, magnetic cards quickly went into every aspect of people's lives.

Magnetic resonance imaging, also known as magnetic resonance imaging, is the use of NMR principles, according to the energy released in material environment within different attenuation by external magnetic field detection of electromagnetic waves emitted, that constitutes the nucleus of the object location and type, which can draw objects within the image. MRI imaging technology applied to the human body, is a revolution in modern medical diagnostic technology.

Magnetic resonance imaging in the "core" refers to the hydrogen atom. We know that in various tissues in the human body contains large amounts of water and hydrocarbons, hydrogen nuclei as preferred body imaging elements have the flexibility of high and signal characteristics. In the intensity of the magnetic field, when the radio frequency pulse signal is applied, hydrogen nuclear States will change Proton will return to the initial state after the RF, electromagnetic waves of resonance will be emitted. Many changes in the pathology of the disease process can cause moisture patterns, can be reflected by magnetic resonance images. Magnetic resonance imaging instruments can be accurately detected Proton vibrations of small differences, so that you can learn that constitutes the object of the Proton location and type of object can be drawn precisely within the stereo image and corresponding pathological changes can be accurately recorded.

Image is very clear and fine obtained by magnetic resonance imaging, high resolution, and parts of the body from many angles, more graphic images, and thus provides more objective and concrete to show the anatomy of the human body tissue and adjacent relationship. Magnetic resonance imaging can not only greatly improve the efficiency of the doctor's diagnosis, but can be used for diagnosis of all systems of the body, especially the early cancer diagnosis. Also, MRI avoids the operation of Thoracotomy or laparotomy diagnosis, and do not use harmful x-ray and vulnerability caused by allergic reactions to contrast agents, so no harm to human body.

Maglev is the world's most technologically advanced and has entered a practical phase of new trains, their typical characteristics are at work in a suspended state. Trains are "suspended", the main objective is to reduce the friction between the train tracks, thus greatly increasing the speed of the train, and energy-saving.

Maglev train consists of magnetic suspension system, propulsion system and guiding system consists of 3 parts. Among them, the Maglev system is a core part of the Maglev. World-wide, maglev trains are mainly two different forms of suspension, exclusion-type magnetic levitation maglev trains and suction. The two different forms of suspension magnet of "same-sex repulsion" and "opposites attract" correspond to the two forms.

Exclusion type of maglev train based on magnet "like charges repel" principle of design, use superconducting magnets in the train the formation of magnetic and orbital formation of magnetic field generated by the coil on repulsion forces on the body suspended in orbit. Because of the gap of locomotive and rail to reduce electromagnetic repulsive force increases when, so electromagnetic repulsion can provide stable support to train and guide. Attract type maglev train is according to magnet "specific phase sucking" of principle design of, it using installation in train sides bogie Shang of suspended electric magnet, in magnetic field role Xia and laying in track Shang of magnet produced of suction makes vehicles "suspended" up, and using electronic technology to guarantee train Shang magnet and track always keep must of spacing, makes bogie and train between of attraction and train of gravity equilibrium, to let train suspended in track Shang run.

Recently, Changsha, Hunan, China's first self-developed trial operation of medium and low speed Maglev railway project open, green traffic so as to write a strong one. Medium and low speed maglev trains belonging to the suction developed by magnetic levitation train, whether stationary or moving can maintain a stable state. The electro-magnetic suspension of Maglev system is separate from the power of propulsion drive system, powered by a car battery, so even in the face of power outages could sustain the suspension and drive to a security zone parking. During the travel period, vehicle battery can be installed in the supporting magnet linear generator to recharge. Maglev propulsion system with linear synchronous motor principle is the same, just put the motor "rotor" put them on the trains, and motor "stator" laying on the track. When you want to track the "stator" power, can push trains by electromagnetic induction the "rotor" rotation, which trains electrical energy into kinetic energy.

World range within, "artificial Sun" research pace gradually speed up, people in vision "artificial Sun" this by control hot fusion reaction for human provides inexhaustible energy of while, also will issued such of questions: "artificial Sun" in work Shi, its internal particles of temperature reached tens of millions of even Shang billion degrees Celsius, than Sun itself of temperature also high, to how for "artificial Sun" this big fireball "prison" does?

To ensure the fusion reaction, you must provide a closed reaction space. In the present technical conditions, none of the material can withstand such high temperatures. In the early 1950 of the 20th century, Soviet scientists have proposed "magnetic confinement" concept, namely the use of closed magnetic field to constrain the behavior of high temperature particles, and bind them in a particular area. In 1954, the Soviet scientists built the first magnetic confinement devices, and named it as "tokamak". "Tokamak" is the Russian abbreviation of coil ring, also known as tokamak. This is a made up of closed magnetic field "containers", as well as a hollow doughnut. Such a special kind of "container" just never see, but this is very convenient, because it is not afraid of any heat.

"The artificial Sun" starts in in the 1980 of the 20th century, and in 1984 and built a tokamak in China first, in 1995 built a new first tokamak in China. Scientists develop superconducting tokamak in China is currently in the Assembly phase, is expected to become the world's first to achieve steady-state operation of superconducting magnets and active cooling structure of tokamak, received international attention.

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