...How to Protect Yourself From Computer Radiation and Laptop Computer EMF Are you reading this on a computer? If you are, then you’re face to face with a potentially dangerous electromagnetic field (EMF) especially to the head and upper body. . The EMFs generated by your screen and machine could be seriously damaging your health. The Bad Effects Of Computer Radiation… We’ll examine the EMF radiation from different types of desktop and laptop computers, what that means for your health, and the SafeSpace products that can protect you while you work, surf and socialize online. What is Computer Radiation & Where Does it Come From? CRT (Cathode Ray Tube) screen radiation - If your desktop monitor (or TV) is a few years old and has a deep cabinet, chances are it’s a CRT. CRTs are by far the most dangerous type of screen. • Few desktop computers are made with CRT screens anymore (though some video gamers still prefer them). • The images produced by CRT screens involve a number of processes, including the front of the tube being scanned downward in a pattern of lines, electron beams “sweeping” an image across the screen by modulating their intensity, a coil generating magnetic field and more. The Health Dangers of CRTs • Small amounts of radiation (x-ray frequencies and others) are emitted as the electrons sweep the screen. • At close range, this radiation (literally pulsating fields of energy) puts biological stress on humans, animals and plants. • CRTs also operate at...
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...this phenomenon quantitatively is known as Faraday’s Law. a b c In this activity you will be asked to use Faraday’s Law to explain why the current induced in a coil and thus the voltage across it changes the way it does when the north or south pole of rod shaped magnet is moved into and then back out of the center of a coil of wire at various speeds. No calculations are required in this activity, just thinking! Figure 1: The north pole of a cylindrical magnet is: (a) moving into the center of a coil of wire; (b) reversing direction; and then (c) moving out of the coil. The coil’s voltage vs. time is recorded with a computer interfaced voltage probe. Theoretical Review: According to Faraday’s Law, at any moment the induced emf (denoted ) across a conducting loop with N turns is equal to –N times the rate of change of the magnetic flux passing through the area enclosed by the loop as described in Eq. 1. (Faraday’s Law) [Eq. 1] Figure 1 shows our rod shaped magnet moving along the coil’s symmetry axis. The plane bounded by the coil has an area, A, and is perpendicular to the axis along which the magnet is moving. Even if the magnetic flux passing through the coil is not uniform or constant, we only need to keep track of how much flux passes through the...
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...BLDC motors can be commutated by monitoring the back EMF signals instead of the Hall sensors. The relationship between the Hall sensors and back EMF, with respect to the phase voltage, is shown in Figure 7. As we have seen in earlier sections, every commutation sequence has one of the windings energized positive, the second negative and the third left open. As shown in Figure 7, the Hall sensor signal changes the state when the voltage polarity of back EMF crosses from a positive to negative or from negative to positive. In ideal cases, this happens on zero-crossing of back EMF, but practically, there will be a delay due to the winding characteristics. This delay should be compensated by the microcontroller. Figure 10 shows a block diagram for sensorless control of a BLDC...
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...capacitor C.There is no provision for the controlling force. WORKING: The operation of the instrument can be understood from the three phasor diagram. The magnetising coil carries a current I and this current produces a flux Φ. If we neglect the resistance of the coil and the iron losses in the core, flux Φ is in phase with current I. Flux Φ, being alternating in nature, induces an emf E in the moving coil. This emf lags behind the flux by 90°. The emf induced circulates a current Im in the moving coil. The phase of this current Im depends upon the inductance L of the moving coil and the capacitance C. In fig. (a), the circuit of the moving coil is assumed to be inductive and therefore current Im lags behind the emf E by an angle α. The torque acting on the moving coil is thus: Td α Im cos(90°+α) In fig (b), the moving coil circuit is assumed to be largely capacitive and therefore current Im leads the emf E by an angle β and therefore the deflecting torque is: Td α Im cos(90°-β) This torque is obviously opposite to what was in the case represented in (a). In fig (c) the inductive reactance is supposed to be equal to the capacitive reactance and, therefore, the circuit is under resonance conditions. Thus the...
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...base station could vary from cell phone to another one even within the same area, depends on the interfering from obstacles such as buildings and trees [3]. Although, cell phones are designed to operate at power levels below a threshold for known thermal effects, radio frequency radiation could produce other kinds of effects, called biological effects. In Figure 1, we show a calculation of specific absorbed radiation (SAR) distribution in an anatomical model of human head positioned next to a 125 mW dipole antenna. The resulted Peak SAR is 9.5 W/kg over 1 mg which is a clear indication of the effect. Abstract The growth in the use of cellular phone has raised the concerns about the possible interaction between the electromagnetic fields (EMF) radiation and the biological effects on human tissues, particularly the brain and the human immune system. These concerns have induced a large volume of research studies. However, most of the previous review studies are concentrated on negative effects and no...
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...Physics Of Field Laboratory Instructor: Prof. Pascia Pceit-17-101P Electromagnetic Induction Michael Faraday formulated that electromotive force (EMF) produced around a closed path is proportional to the rate of change of the magnetic flux through any surface bounded by that path. In practice, this means that an electric current will be induced in any closed circuit when the magnetic flux through a surface bounded by the conductor changes. This applies whether the field itself changes in strength or the conductor is moved through it. In mathematical form, Faraday's law states that: where is the electromotive force ΦB is the magnetic flux. For the special case of a coil of wire, composed of N loops with the same area, the equation becomes A corollary of Faraday's Law, together with Ampère's law and Ohm's law is Lenz's law: The EMF induced in an electric circuit always acts in such a direction that the current it drives around the circuit opposes the change in magnetic flux which produces the EMF Electromagnetic induction is the production of an electric current across a conductor moving through a magnetic field. It underlies the operation of generators, transformers, induction motors, electric motors, synchronous motors, and solenoids.[1] Michael Faraday is generally credited with the discovery of induction in 1831 though it may have been anticipated by the work of Francesco Zantedeschi in 1829.[2] Around 1830[3] to...
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...Ruzaini (20) Daniel Deskar (6) Tijany Sulaiman (28) 1. What is electric current? A movement or flow of electrically charged particles, typically measured in amperes. An electric current is a flow of electric charge. In electric circuits this charge is often carried by moving electrons in a wire. It can also be carried by ions in an electrolyte, or by both ions and electrons such as in a plasma. Electric current can consist of a flow of charged particles in either direction. The conventional symbol for current is I 1. Working principles of Electric Current....
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...48550 Electrical Energy Technology Chapter 6. Synchronous Machines Topics to cover: 1) Introduction 2) Synchronous machine structures 3) Rotating magnetic field 4) Equivalent circuit model 5) Performance as a generator 6) Performance as a motor Introduction A synchronous machine is an ac rotating machine whose speed under steady state condition is proportional to the frequency of the current in its armature. The magnetic field created by the armature currents rotates at the same speed as that created by the field current on the rotor, which is rotating at the synchronous speed, and a steady torque results. Synchronous machines are commonly used as generators especially for large power systems, such as turbine generators and hydroelectric generators in the grid power supply. Because the rotor speed is proportional to the frequency of excitation, synchronous motors can be used in situations where constant speed drive is required. Since the reactive power generated by a synchronous machine can be adjusted by controlling the magnitude of the rotor field current, unloaded synchronous machines are also often installed in power systems solely for power factor correction or for control of reactive kVA flow. Such machines, known as synchronous condensers, may be more economical in the large sizes than static capacitors. With power electronic variable voltage variable frequency (VVVF) power supplies, synchronous motors, especially those with permanent magnet rotors, are widely used...
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...A Review of Induction Motors Pattinson Hayton California State University, Long Beach College of Engineering 12/03/2015 Thus far in Energy Conversion and Principles, the topics of direct current, or DC, and synchronous motors have been covered and discussed. A direct current exists in the field windings of both of these motors and an alternating current, or AC, exists in the armature windings of both of these motors. Electrical power is delivered right to the armature of a DC motor using a commutator, or the moving part of the rotary, in these motors. Because of this, a DC motor with this type of connection can also be referred to as a conduction motor. Conversely, if a motor receives power by induction, rather than by conduction, the motor is called an induction motor. An induction motor is therefore a type of transformer that possesses a rotary secondary winding. As discussed previously, both DC and synchronous motors are doubly-fed. An induction motor, however, is a singly-fed motor. With these motors being singly-fed, the construction of is different than that of other motors. These motors do not require slip-rings, a commutator, or brushes. With these components absent from induction motors, it is thus seen that there are no moving contacts between the stator and rotors, which is obviously quite different than the structure of DC and synchronous motors. Induction motors are useful due to their efficiency. The absence of brushes in induction motors eliminates...
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...& Flux: Ampere’s Law & Faraday’s Law Physics 204, Yaverbaum John Jay College of Criminal Justice, the CUNY (The following consists of 4 problems) I. A long coaxial cable, a section of which is shown above, consists of a solid cylindrical conductor of radius a, surrounded by a hollow coaxial conductor of inner radius b and outer radius c. The two conductors each carry a uniformly distributed current I, but in opposite directions. The current is to the right in the outer cylinder and to the left in the inner cylinder. Assume µ = µo for all materials in this problem. a. Use Ampere's law to determine the magnitude of the magnetic field at a distance r from the axis of the cable in each of the following cases. i. 0 < r < a ii. a < r < b b. What is the magnitude of the magnetic field at a distance r = 2c from the axis of the cable? c. On the axes below, sketch the graph of the magnitude of the magnetic field B as a function of r, for all values of r. You should estimate and draw a reasonable graph for the field between b and c rather than attempting to determine an exact expression for the field in this region. II. The coaxial cable continues to carry currents I as previously described. In the cross section above, current is directed out of the page toward the reader in the inner cylinder and into the page in the outer cylinder. Point P is located between the inner and outer cylinders, a distance r from the center. A small positive charge q is introduced into the space between...
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...22. In the circuit shown above, what is the value of the potential difference between points X and Y if the 6-volt battery has no internal resistance? A) 1 V A) 2 V B) 3 V C) 4 V D) 6 V Total resistance 4 Ω + ( 1/3 Ω + 1/6 Ω)-1 = 6 Ω Current = I = V/R 6 V / 6 Ω = 1 A V = 1 A 4 Ω = 4 V Therefore 2 V will be left for the parallel network More glow more flow [pic] 23. A lamp, a voltmeter V, an ammeter A, and a battery with zero internal resistance are connected as shown above. Connecting another lamp in parallel with the first lamp as shown by the dashed lines would A) increase the ammeter reading A) decrease the ammeter reading B) increase the voltmeter reading C) decrease the voltmeter reading D) produce no change in either meter reading Questions 24-25 relate to the five incomplete circuits below composed of resistors R, all of equal resistance, and capacitors C, all of equal capacitance. A battery that can be used to complete any of the circuits is available. 24. Into which circuit should the battery be connected to obtain the greatest steady power dissipation? D 25. Which circuit will retain stored energy if the battery is connected to it and then disconnected? B because the capacitor can not discharge 26. A parallel-plate capacitor is charged by connection to a battery. If the battery is disconnected and the separation between the plates is increased, what will happen to the charge on the...
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...The International Journal Of Engineering And Science (IJES) ||Volume|| 2 ||Issue|| 11 ||Pages|| 25-27 ||2013|| ISSN (e): 2319 – 1813 ISSN (p): 2319 – 1805 Electricity Generation from Speed Breakers 1 1, 2, 3 Aniket Mishra, 2Pratik Kale, 3Atul Kamble Department of Mechanical Engineering, Bharati Vidyapeeth college of engineering ---------------------------------------------------------ABSTRACT----------------------------------------------------------Energy is the primary need for survival of all organisms in the universe. Everything what happens in the surrounding is the expression of flow of energy in one of the forms. But in this fast moving world, population is increasing day by day and the conventional energy sources are lessening. The extensive usage of energy has resulted in an energy crisis over the few years. Therefore to overcome this problem we need to implement the techniques of optimal utilization of conventional sources for conservation of energy. My paper includes how to utilize the energy which is wasted when the vehicles passes over a speed breaker. Lots of energy is generated when vehicle passes over it. We can tap the energy generated and produce power by using the speed breaker as power generating unit. The kinetic energy of the moving vehicles can be converted into mechanical energy of the shaft through rack and pinion mechanism. Then, this mechanical energy will be converted to electrical energy using generator which will be saved...
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...Leeds Metropolitan University 4/30/2012 IFM PLC | Consultancy Report | Financial Analysis and assessing future options for the company | Mohamed Kamara and Iwi Ugiagbe-Green Jens Hagenbeck ID: 33269369 Executive Summary This consultancy report aims at the Board of Directors of IFM Plc a multinational company providing financial services and was being ordered by Finance Director Mrs. Diana Worth. It analyses and evaluates a prospective joint venture between a German subsidiary and EMF Plc, re-domiciling the parent company from France to Monaco and expanding into Asia. The financial analysis showed that a joint venture requires an €2 million investment, which could be funded by the shareholders offering a yield of return of 12%. Using the financial data provided and calculating the weighted average cost of capital and the Net Present Value, a WACC of 10% and a NPV of €2.051 million were the results, proving the worthiness of the investment into the joint venture. Before signing any agreements further research needs to be taken to evaluate non-financial aspects such as opportunity costs and other investments. The second part of the report deals with the re-domiciling of the parent company from France to Monaco. From a business perspective and logical point of view this step makes sense as a lot of business operations are being run in Monaco, but it could still damage the company’s image to move from France just for profit and also shareholders might...
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...the magnetic field in the middle of the pickup coil. Your screen should look something like what you see to the right, on Screen 1. When the light bulb lights up it indicates the electricity has been generated. Grab the magnet and move it around and observe what happens to the strength of the magnetic field and to the light bulb. Based on your observations what conditions must happen for electricity to be generated. Answer: Observations-As the magnetic field is moved from the bottom of the coil and moves around the coil from left to the top and then the right, the strength of the magnetic field increased; therefore, it can be concluded that the strength of the magnetic field affects the amount of electricity generated. 3. Make observations & draw conclusions. Move the magnet back and forth, fast and then slow. What general rule can you make about the speed of the magnet and electrical generation? Answer: Observations- Flux is proportional to the field strength. It depends on the rate of change of the magnetic field, moving the magnet quickly will result in a higher generation of electricity. 4. Make observations & draw conclusions. Leave the magnet in just one place and using the button on the right control panel of the applet, flip the polarity of the magnet. Flip the polarity of the magnet fast then slow and observe the amount of electricity that is generated. What general rule can you make about...
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...Cell phones and brain cancer Now a days everyone has a cell phone. People of all ages rely on their cell phone for daily tasks. How many times a person feels absolutely powerless without a cell phone? Which leads us to a very important question. What type of damage does the use of cell phone causes in the brain? The purpose of this paper is to explore if there is evidence that will link cell phone use and brain cancer. There has been a tremendous increase of cell phone use that is starting at a young age. This means a longer exposure to cell phones throughout life. Currently, people do not seem preoccupied with the idea of brain cancer. There are no reports of cell phone use decrease from consumers. People start using cell phone at a younger age every year. Middle school admission paper work requests student’s cell phone number to inform emergency situations, which leads to pressure to parent to get the student a phone. Some people are abstaining from traditional phone line service in their homes. Phones lines can be seen as waste of money since cell phone use is more prominent in some households. University of Great Fall’s library research data base was used to search for evidence that will link cell phone use and brain cancer. The keywords used where “cell phone use and brain cancer.” The Bosnian Journal of Basic Medical Science reviewed total of 30 studies on mobile phones, all but one were case-control studies (Bayazit, Bayram, Pala, & Atan, 2010, p. 246). The...
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