Basic Principles Of Electromagnetism Research Articles

Unveiling confinement in pure gauge SU(3): flux tubes, fields, and magnetic currents

A characteristic signature of quark confinement is the concentration of the chromoelectric field between a static quark–antiquark pair in a flux tube. However, the structure of this flux tube, and hence of the confining force, has not been completely understood. Here we perform new lattice measurements of field distributions on smeared Monte Carlo ensembles in SU(3) gauge theory. On the basis of these simulations we demonstrate that the confining force can be understood using the analogy with the basic principles of electromagnetism as elucidated by Maxwell. We derive a chromomagnetic Lorentz force density coupling the chromoelectric field to chromomagnetic currents and integrate this force density over the flux tube interior to obtain a Maxwell-like force that squeezes the flux tube in the transverse direction. We show that the strength of this transverse confining force is equal to the value of the string tension calculated numerically from the chromoelectric field on the midplane between the quarks, verifying the consistency of these two complementary pictures of confinement.

Tratamento experimental do protótipo de um motor de corrente contínua

Esse trabalho tem como objetivo apresentar os resultados do estudo analítico e experimental do protótipo de um motor de corrente contínua desenvolvido experimentalmente. Esse motor tem como princípio da ação motora, as forças repulsoras entre ímãs ou eletroímãs. Teve como base fundamental para análise das forças, campo e torque atuante no rotor as leis da magnetostática, tais como a Lei de Ampére e a Lei de Biot Savart, além de conceitos relacionados ao princípio de funcionamento de um motor de corrente contínua. Para modelagem do experimento utilizou-se o software SketchUp, uma ferramenta que permite a construção de modelos geométricos, modelos físicos e por fim, um protótipo, permitindo dar um posicionamento estratégico as bobinas, rotor e estator, tendo como objetivo principal da modelagem, apresentar um experimento com características de um motor elétrico e que sua estrutura apresente semelhança com as exemplificações feitas em livros didáticos. Na construção do protótipo foi utilizado elementos de baixo custo, aproveitando componentes de equipamentos descartados. Os resultados obtidos através dos estudos analíticos e testes experimentais permite visualizar um adequado funcionamento do protótipo, possibilitando sem muitas complicações visualizar diversos tópicos abordados no curso de física e engenharia, tais como, campos magnéticos gerado por bobinas, força magnética, torque em uma espira, força magnética em um fio percorrido por corrente, velocidade de um rotor composto por bobinas imerso em um campo magnético e momento dipolar, além de sua estrutura permitir chegar a resultados matemáticos acerca de seu funcionamento, usando princípios básicos do eletromagnetismo..

Hyperloop Transportation System: Analysis, Design, Control, and Implementation

This study introduces a novel methodology based on an extensive mathematical analysis, performed from basic electromagnetic principles, with an optimized cost for a magnetic levitation Hyperloop system. This new approach uses both permanent magnets and electromagnets to levitate, propel, and control a pod. The electrodynamic suspension system is emulated as a small pod attached with permanent magnets from the bottom, which resembles a short-rotor linear synchronous motor. A comprehensive finite-element analysis using ANSOFT Maxwell software on the effects of the magnetic field distribution of the coils due to the ac current flowing through them is investigated. The effects of the magnetic force exerted on the permanent magnet secondary are examined as well. The whole magnetic levitation system prototype was implemented in the laboratory as a proof of concept in order to validate and verify the simulation results. The simulation results are in full agreement with the mathematical analysis, which assures the validity of the design procedure and the magnetic analysis.

Analytical results for rotating and linear magnetic brakes

A theory of magnetic damper (eddy-current brake) which can be applied to axial-flux rotating and linear systems moving under the influence of an arbitrary arrangement of magnetic poles is derived from basic electromagnetic principles. Analytical expressions for the braking forces and torques are obtained in the low-velocity limit of the moving nonmagnetic conductor.

Simulation Study on the Force of Particles Migrating in Molten Metal under High-Frequency Magnetic Field

According to the basic principles of electromagnetism, the magnetic flux density on the surface of the metal melt was calculated by numerical simulation method. The relational expression of the electromagnetic body force and the magnetic flux density was deduced. The results show that the electromagnetic body force in the melt is directly proportional to the square of the magnetic induction intensity. Increasing the electric current, the electromagnetic body force in the melt can be increased effectively. Increasing the frequency, the particular electromagnetic body force within the melt can be increased first and then decreased.

Measurement of Helmholtz Coil

Based on the basic principles of electromagnetism, the application of Shanghai Fudan-day Welcomes UNESCO Instruments Ltd. THQHC-1 type Helmholtz coil magnetic field measuring instrument for measuring coil uniform magnetic field generates a magnetic field on the carrier to get round the coil axis, online circle center at (coordinate origin) at the maximum magnetic field strength. Starting from the coordinate origin, to the sides, the magnetic field lines accelerate the decline, when the distance exceeds the coil radius, the decelerating decline. Conclusions for the understanding of a uniform magnetic field reference.

Use of a varying turn-density coil (VTDC) to generate a constant-gradient magnetic field and to demonstrate the magnetic force on a permanent magnet

In this study, we proposed that a constant gradient magnetic field could be generated by the construction of a current-carrying coil possessing a turn-density (number of turns per unit length) that varies linearly with axial position (i.e., a varying turn-density coil, VTDC). A VTDC is easily constructed and could be used to demonstrate how a ferromagnet placed in a magnetic field experiences a net force. Using the Biot–Savart law, we predicted that a ferromagnetic dipole suspended in a VTDC experiences a force proportional to the length of the dipole. We designed and executed an experiment to test our prediction. A coil with a turn-density varying at a rate of 0.11 cm−2 was constructed. Rare-earth magnets were suspended along the centre of the VTDC using a string that was attached to a mass resting on a scale. The scale reading measured the force experienced by the hanging magnet. The procedures were also carried out in a constant turn-density solenoid (control). A direct linear relationship between force and magnet length was observed in the VTDC, whereas no force was detected in the zero-gradient field solenoid (p < 0.000 001). Linear regressions suggested that the observed data matched the predicted values (95% certainty). The magnetic moment of 0.56 ± 0.21 J/T is in reasonable agreement with remnant magnetization for neodymium magnets of ∼1 T. We found that our easily-built VTDC produced a uniform gradient as no significant differences were observed when magnets were hung at different axial positions. Overall, the results were supportive of the theory. Our VTDC could be readily constructed and used in a physics classroom to demonstrate basic principles of electromagnetism.

Circuit model for coupling between MMICs in multichip modules including resonance effects

This paper describes a circuit model to be used for the approximate calculation of coupling between monolithic microwave integrated circuits (MMICs) in a multichip module. The model is developed from basic electromagnetic principles and relies on the formation of equivalent electric dipoles to represent the complex currents on the various MMICs within the module. The technique is suitable for use in layout-based circuit simulators and uses no numerical analysis.

A miniature pan-tilt actuator: the spherical pointing motor

A pan-tilt mechanism is a computer-controlled actuator designed to point an object such as a camera sensor. For applications in active vision, a pan-tilt mechanism should be accurate, fast, small, inexpensive and have low power requirements. The authors have designed and constructed a new type of actuator meeting these requirements, which incorporates both pan and tilt into a single, two-degree-of-freedom device. The spherical pointing motor (SPM) consists of three orthogonal motor windings in a permanent magnetic field, configured to move a small camera mounted on a gimbal. It is an absolute positioning device and is run open-loop. The SPM is capable of panning and tilting a load of 15 grams, for example a CCD image sensor, at rotational velocities of several hundred degrees per second with a repeatability of .15/spl deg/. The authors have also built a miniature camera consisting of a single CCD sensor chip and miniature lens assembly that fits on the rotor of this motor. In this paper, the authors discuss the theory of the SPM, which includes its basic electromagnetic principles, and derive the relationship between applied currents and resultant motor position. The authors present an automatic calibration procedure and discuss open- and closed-loop control strategies. Finally, the authors present the physical characteristics and results of their prototype.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">&gt;</ETX>

Deduction of generalised Kirchhoff's Laws from the basic principles of electromagnetism

The deduction of the so well-renowned and established Laws of Kirchhoff relating to the currents flowing in a network, which are considered to be almost axiomatic in electrical engineering sciences, seems to be preposterous and non-sensical at first sight. However, on a closer examination it will appear that these laws are based on two principles, viz, the steady-state condition under which accumulation of free electrical charge is precluded, and, the experimentalOhm's Law, which propounds a linear relation between the difference of potential across a conductor and the total current flowing through the same. But, there are two things, which are normally overlooked. The conductors inKirchhoff's Laws are “wires”, which are one-dimensional lines, and theOhm's Law is the macroscopicOhm's Law for total currents applied to these lumped resistors. Strictly speaking, the “Laws” are to be deduced from the more fundamental electromagnetic equations for continuous media and the microscopicOhm's Law. It is to be noted that theKirchhoff Nodal Law is but a consequence of the steady state condition derivable from these basic equations, viz, the current-density is divergence-free. For a continuous medium, what the form of theKirchhoff's Laws will be, is difficult to guess unless deduced from the basic equations. Once these are established from the basic equations of electromagnetism for a continuous medium, the usual form ofKirchhoff's Laws will follow as corollary of the general case, as has been shown here.