...Episode 412: The force on a conductor in a magnetic field Having reminded your students that magnetic fields can be found near permanent magnets and in the presence of an electric current, the next step is to show how the ‘field’ can be quantified. Again, students should know that a conductor carrying a current in a magnetic field will experience a force and will probably remember that Fleming's Left Hand Rule can be used to find the direction of that force. Summary Demonstrations: Leading to F = BIL. (15 minutes) Discussion: Factors affecting the force. (15 minutes) Discussion: Formal definitions. (20 minutes) Student questions: BIL force calculations. (20 minutes) Demonstrations: Leading to F = BIL Several quick experimental reminders are possible. Tap 412-1: Forces on currents TAP 412-2: An electromagnetic force These lead on to a further experiment in which the relationship F=BIL can be established. TAP 412-3: Force on a current-carrying wire Discussion: Factors affecting the force The experiments above lead to the conclusion that the force F on the conductor is proportional to the length of wire in the field, L, the current I and the ‘strength’ of the field, represented by the flux density B. (There is also an 'angle factor' to consider, but we will leave this aside for now.) Combining these we get F = BIL (It can help students to refer to this force as the ‘BIL force’.) Students...
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...CHAPTER 1 INTRODUCTION 1.1 General The micro-emulsion inks have a wide range of applications in industry. The ink used earlier for printing purposes contributes to pollution in environment. The pollution is by means of emission of volatile organic compounds (VOCs) which are present in the form of an aliphatic solvent. Emission of VOCs from these solvents and their discharge in waste streams are quantifiable. For example a typical medium size cold – set web plant uses 40,000 kg per year of the ink of which 6000 kg is lost as emissions. The plant uses over 10,000 kg per year of cleaning solutions all of which is lost in atmosphere. A typical newspaper uses 100,000 kg per year of ink and emits over 8000 kg of volatile solvents (Maji, 2003). VOC when released into the atmosphere participates in the atmospheric photochemical reactions. Ozone is produced at the ground level when oxides of nitrogen and VOCs react in the presence of sunlight. This is a major component of urban smog, which at elevated levels causes a potential hazard to humans, plants and animals. To overcome the problems of emissions due to solvent-based inks and cleaning of presses, a new type of ink based on vegetable oil has been developed which is biodegradable and environment-friendly. It does not contain aliphatic solvents, and hence its use produces virtually no emissions during printing. Also, this ink contains vegetable oil (castor-oil)-based alkyd resins, which are biodegradable and generate no...
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...Brushless Direct Current (BLDC) motors are one of the motor types rapidly gaining popularity. BLDC motors are used in industries such as Appliances, Automotive, Aerospace, Consumer, Medical, Industrial Automation Equipment and Instrumentation. As the name implies, BLDC motors do not use brushes for commutation; instead, they are electronically commutated. BLDC motors have many advantages over brushed DC motors and induction motors. A few of these are: • Better speed versus torque characteristics • High dynamic response • High efficiency • Long operating life • Noiseless operation • Higher speed ranges In addition, the ratio of torque delivered to the size of the motor is higher, making it useful in...
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...Sim_____________________________________________ Role | I | DC | AD | RC | Q1 | Q2 | PI | PG | | | | | | | | | | | | | | | | | | | | | | | | | | | | I introduction DC data and calculation AD analysis and discussion RC results and conclusion Q1/Q2 quiz/prelab PI principal investigator points PG personal grade Introduction: The purpose of the lab is to study the effects due to magnetic fields in motion and also to determine the qualitative features of electromagnetic induction. Procedure: 1. For the Part 1 of the lab, a solenoid was connected to a galvanometer, as shown in the data and calculations. First, the North pole was inserted into the coil, then in the opposite direction, with the South Pole first. Then, the magnitude and sign of the deflection on the galvanometer was recorded in μAmps. Also, an exact sketch is made of the solenoid, the direction of the velocity, the induced magnetic field, the induced current and the magnetic polarity of the solenoid induced in provided in the data and calculations portion of the report. 2. The magnet was inserted again following step 1, but with a faster speed and everything sketched again. Then, The South pole was inserted first and step 1 followed again for both, slow and fast speed. 3. For Part II of the lab, an electromagnet was constructed with the power supply off. In this set up the primary coil had a larger diameter wire and...
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...freshman students (68.6% of all 2008 high school graduates) were enrolled in college as of October of that year. Children are afforded the opportunity to get a descent education no matter where they are from, where they grew up, or what economic class they live in but some don’t get to attend college. The environmental surroundings affect how well juveniles receive an education. Young people will be put under a lot of stress and pressure from school work and activities. These young people of this generation will be slowly replacing the older generation workers. Getting a good paying job, these young people will need A.S., A.A, B.S., MBA, and PhD degrees. Children can achieve these degrees by attending either public, private, parochial, magnet, or charter schools. Public schools are paid for by local, state, and federal government funds. With every year the country’s budget gets smaller and smaller due to economic problems. City school boards have had to cut some teachers because they don’t have the funding to pay them. This increases the student to teacher ratio, causing less quality of service for each student. In 2008-09 school year, 49,265,044 students graduated public high school nationally with student to teacher ratio 15.3 (Public, 2011). The majority of these schools are located in low income...
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...Design of a Small-Scale Prototype for a Stabilized Permanent Magnet Levitated Vehicle No. 88 Geoffrey A. Long, O. James Fiske, Brad E. Paden LaunchPoint Technologies, Goleta, California, USA glong@launchpnt.com, jfiske@launchpnt.com, bpaden@launchpnt.com ABSTRACT: A small-scale proof-of-concept prototype has been designed and built as the next stage in the development of a novel maglev vehicle concept. This prototype demonstrates many of the key advantages of the technology which uses permanent magnets for levitation and does not require any moving parts in a track bifurcation. Key design features and performance characteristics of the prototype are described: the control system for stable levitation, the linear synchronous motor for propulsion and the method of track switching. Alternative system configurations and other applications of the technology are also briefly discussed. 1 INTRODUCTION The repelling forces resulting from bringing like poles of two magnets together is a commonly experienced phenomenon. The use of this repelling force to levitate a vehicle was considered early in the exploration of maglev vehicle technologies (Pollgreen 1964, Olsen 1965), but was largely discarded due to poor performance of the magnetic materials available at the time. As SmCo materials became available, the approach was revisited but again set aside by most due to the material’s high cost (Sinha 1987). In the 1980’s and 90’s NdFeB materials began to be developed as a low cost alternative...
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...3-D image of the body The MRI unit has an extremely strong magnet so patients should avoid wearing jewelry and other accessories because they could interfere with the magnetic field. Items not allowed to enter the exam room: * Jewelry, watches, credit cards, and hearing aids (all can be damaged) * Pins, hairpins, metal zippers, and similar metallic items (can alter Images) * Pen, pocketknives, eyeglasses Most of the time, the MRI scan is safe for patients who have metal implants, the technologist should know if the patient has a devices in their body. * Artificial Heart Valves * Implanted Drug Infusion Parts * Implanted Nerve Stimulators * Implanted electronic devices * Artificial Limbs or Metallic Joints Prostheses * Metal Screws, Plates, or Surgical Stapes If there is any doubt about the presence of metal in the body an x-ray should be taken. Very rarely, dyes used in tattoos contain iron which may heat up during an MRI scan. Other things to keep in mind before you receive a MRI: * Patients with claustrophobia or anxiety may want to request a mild sedative * If the MRI scan will involve taking a contrasting agent, the patient should tell the provider about any allergies including hay fever, hives, allergic asthma, of food and drug allergies * If the patient has any type of serious health problems such as kidney disease or sickle cell anemia because it may effect whether or not contrasting agent is used with the MRI *...
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...Preliminary Course Assessable Task 1 By Edward Hawkins 09.04.13 Title Page | p. 1 | Part A: Historical Developments * Materials * Transport * Tool-Making * Chemical Knowledge * Communication Knowledge * ElectricityPart B: Electric Motors: * Diagram: DC motor * Rotating Magnetic Fields in an Electric Motor | p. 3 | | p. 3 | | p. 3 | | p. 4 | | p. 5 | | p. 6 | | p. 7 | | p. 8 | | p. 8 | | p. 8 | Bibliography | p. 9 | Table of Contents Part A: Historical Developments Materials: Salvinia Molesta Mimic Salvinia Molesta hairs Salvinia Molesta hairs The Brazilian fern Salvinia molesta has proliferated around the Americas and Australia in part because its surface is dotted with oddly shaped hairs that trap air, reduce friction, and help the plant stay afloat. In the November 1 issue of the Journal of Colloid and Interface Science, Ohio State University engineers describe how they recreated the texture, which resembles a carpet of tiny eggbeater-shaped fibers. In nature, air pockets trapped at the base of Salvinia's hairs reduce friction in the water and help the plant float, while a sticky region at the tips of the eggbeaters clings lightly to the water, providing stability. In tests, the coating performed just as the Salvinia hairs do, the bases of the hairs were hydrophobic, while the tips of the hairs were hydrophilic and so water droplets did not penetrate between the hairs, but instead clung to the tops of the eggbeater...
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...Its is one of two ways to expressed a magnetic intensity. SI unit of measurement = Ampere per metre (A/m) SI symbol = ’H’ H = MMF / L = IN / L where ‘L’ is the length of the coil The Magnetic Field Strength is inversely proportional to the length of the soil. The longer the length the lesser the magnetic field strength. 7) Induction There are 2 laws of induction - Faraday’s and Lenz’s Laws. Faraday’s Law states that a changing magnetic flux passing a conductor will induce an EMF and the size of the induced EMF is proportional to the rate of change of flux. Lenz’s Law states that an induced EMF generates a current that induces a counter magnetic field (Field B) that opposes the magnetic field (Field A) generating the current. Faraday’s Law states the relationship between rate of change of magnetic flux to induced EMF. Lenz’s Law defines the polarity of the induced EMF. Therefore a combination of the the two is optimal in defining...
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...slows the flow of the electrons, reducing the current in the circuit. We will use the mathematical form of Ohm’s Law frequently when we investigate electric current and circuits later in this unit. Additional Material Needed: Clean Drinking Straw Procedure Part I Wire Resistance: • Blow through the drinking straw. • Cut the drinking straw in half and blow through a half-straw. • Describe the effect of length on ease to blow air through the straw. There is more resistance when the straw is longer. • Cut the halves again in half. • With the four pieces, blow through one, then blow through all four made into a larger, square-shaped straw. • Describe the effect of straw size (diameter) on ease to blow air through the straw. Less resistance • Now, open the PhET Simulation Electricity, Magnets, and Circuits ( Resistance in a Wire[pic] As wire length (cm) increases, the resistance (Ω) INCREASES As wire area (cm2) increases, the resistance (Ω) DECREASES As wire density (Ωcm) increases, the resistance (Ω) STAYS THE SAME Procedure Part II: Ohm’s Law: Electricity, Magnets, and Circuits ( Ohm’s Law [pic] mA is milliamps, and 1000 milliamps equals one Ampere. • Move the potential (volts) and resistance (ohms) sliders and observe the current (amps) As voltage increases, current INCREASES As resistance increases, current DECREASES. Fill out the tables below and check your work in the simulation. ( ½ pt each ) • Remember, the simulation shows milliamps. • You...
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...GCSE Physics Revision notes 2014 Contents Static and Current Electricity .............................................................................................................. 2 Properties of Waves ........................................................................................................................... 12 Uses of Waves..................................................................................................................................... 13 Forces, Moments and Pressure......................................................................................................... 14 Energy Transfers................................................................................................................................. 17 Energy Calculations ............................................................................................................................ 20 Radioactivity ........................................................................................................................................ 22 Magnetism and Electromagnetism ................................................................................................... 24 Space .................................................................................................................................................... 27 These notes cover the main areas of this subject. Please check the specific areas you need with your exam board. They are...
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...for Permanent-Magnet Synchronous Machines Chun-Yu Hsiao *, Sheng-Nian Yeh and Jonq-Chin Hwang Department of Electrical Engineering, National Taiwan University of Science and Technology, Taipei 10607, Taiwan; E-Mails: snyeh@mail.ntust.edu.tw (S.-N.Y.); jchwang@ee.ntust.edu.tw (J.-C.H.) * Author to whom correspondence should be addressed; E-Mail: D9607101@mail.ntust.edu.tw; Tel.: +886-921135781; Fax: +886-2-27376699. Received: 16 September 2011; in revised form: 22 November 2011 / Accepted: 30 November 2011 / Published: 6 December 2011 Abstract: Cogging torque exists between rotor mounted permanent magnets and stator teeth due to magnetic attraction and this is an undesired phenomenon which produces output ripple, vibration and noise in machines. The purpose of this paper is to study the existence and effects of cogging torque, and to present a novel, rapid, half magnet pole pair technique for forecasting and evaluating cogging torque. The technique uses the finite element method as well as Matlab research and development oriented software tools to reduce numerous computing jobs and simulation time. An example of a rotor-skewed structure used to reduce cogging torque of permanent magnet synchronous machines is evaluated and compared with a conventional analysis method for the same motor to verify the effectiveness of the proposed approach. The novel method is proved valuable and suitable for large-capacity machine design. Keywords: cogging torque; permanent magnet; finite element...
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...interaction between the magnetic field in the stator and rotor. The strength of the magnetic fields is proportional to the amount of current sent to the stator and the number of turns in the windings. The stepper motor uses the theory of operation for magnets to make the motor shaft turn a precise distance when a pulse of electricity is provided. You learned previously that like poles of a magnet repel and unlike poles attract. Figure 1 shows a typical cross-sectional view of the rotor and stator of a stepper motor. From this diagram you can see that the stator (stationary winding) has eight poles, and the rotor has six poles (three complete magnets). The rotor will require 24 pulses of electricity to move the 24 steps to make one complete revolution. Another way to say this is that the rotor will move precisely 15° for each pulse of electricity that the motor receives. The number of degrees the rotor will turn when a pulse of electricity is delivered to the motor can be calculated by dividing the number of degrees in one revolution of the shaft (360°) by the number of poles (north and south) in the rotor. In this stepper motor 360° is divided by 24 to get 15°. When no power is applied to the motor, the residual magnetism in the rotor magnets will cause the rotor to detent or align one set of its magnetic poles with the magnetic poles of...
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...INTRODUCTION MAGNETIC LEVITATION TRASPORT, OR MAGLEV, IS A FORM OF TRANSPORTATION THAT SUSPENDS, GUIDES AND PROPELS VEHICLES VIA ELECTROMAGNETIC FORCE Air flights are and will remain beyond the reach of a major section of society, particularly in India. Moreover there are problems of wastage of time in air traffic delays and 2 growing safety concerns. Trends in increased mobility of large masses with changing lifestyle for more comfort are leading to congestion on roads with automobiles. Besides, increasing pollution levels from automobiles, depleting fuel resources, critical dependence on the fuel import and due to a limited range of mobility of buses and cars the need for fast and reliable transportation is increasing throughout the world. High-speed rail has been the solution for many countries. Trains are fast, comfortable, and energy-efficient and magnetic levitation may be an even better solution.Development of magnetic levitated transport systems is under progress in developed countries and it is just a matter of time they make inroads to India as well. Therefore, it will be interesting to know about the science and technology behind mass ground transport system known as "magnetic flight". A LITTLE HISTORY In 1922 a German engineer named Hermann Kemper recorded his first ideas for an electromagnetic levitation train. He received a patent in 1934 and one year later demonstrated the first functioning...
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...Maglev can provide this speed and compete directly with airline travel. As stated by American Maglev, "Maglev means magnetically levitated and propelled vehicles. The advantage of maglev is that it can achieve very high speed and acceleration/deceleration performance because the vehicles essentially "fly" at very low altitudes - unlike trains or cars; there is no surface contact or "friction" to slow them down. More speed = more passengers." Only when we have real revenue-producing systems in operation will be able to prove whether this is true or not. In Maglev—which is short for MAGNETIC LEVITATION—high speed vehicles are lifted by magnetic repulsion, and propelled along an elevated guide way by powerful magnets attached to the vehicle. The vehicles do not physically contact the guide way, do not need engines, and do not burn fuel. Instead, they are magnetically propelled by electric power fed to coils located on the guide way. Indeed this is the beginning of the trans- rapid transportation that the human race would view out in the coming centuries. It’s not only just about trains but also the future of high speed trains which would compete with airplanes rather enhancing the leisure part of the whole human race. INTRODUCTION : Magnetic levitation transportation is poised as the next generation of high-speed travel. The...
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