The Electromagnetic Field and People
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Electromagnetic Fields
ELECTROMAGNETIC FIELDS Measure: Why? • Measurement determines whether the • Measurement gives facts. For example, limit values for electromagnetic radiation public protection: On site measurements specified in laws, national regulations, and show the actual exposure levels. This can recommendations are being adhered to. help to allay unfounded anxiety, and can This is essential for occupational safety and be used to initiate further preventive action to protect the general public. – even if the values are well below the permitted limits. • Measurement gives reassurance. It is the most important step in effective protection. • Measurement makes sure. For instance, Take maintenance work on an antenna when planning high tension transmission array, for example: Are the transmitters lines or antenna arrays, spot check measure- switched off? Or is the field strength safe? ments show whether the field strength Do the actual values agree with the theor- simulation used in planning corres ponds to etical ones? reality. MEASURE: WHY? Measure: How? • Only standard-compliant measurements • Non-directional (isotropic) measurement is provide comparable, reproducible, and demanded by the standards. legally defensible results. • The permitted field strengths depend on • The measurement results must be under- the frequency. The measuring instrument standable, even for someone who is not must therefore be sensitive enough, have constantly concerned with electromagnetic a wide dynamic range, and be capable of fields. frequency selective field strength evaluation complying with regulations. • The electric and magnetic fields must be measured separately in the near field. • If the field strength is high or unknown, fit the instrument on a tripod and measure by remote control. MEASURE: HOW? Measure right! • Measurement means comparison with a known quantity. -
Electromagnetism As Quantum Physics
Electromagnetism as Quantum Physics Charles T. Sebens California Institute of Technology May 29, 2019 arXiv v.3 The published version of this paper appears in Foundations of Physics, 49(4) (2019), 365-389. https://doi.org/10.1007/s10701-019-00253-3 Abstract One can interpret the Dirac equation either as giving the dynamics for a classical field or a quantum wave function. Here I examine whether Maxwell's equations, which are standardly interpreted as giving the dynamics for the classical electromagnetic field, can alternatively be interpreted as giving the dynamics for the photon's quantum wave function. I explain why this quantum interpretation would only be viable if the electromagnetic field were sufficiently weak, then motivate a particular approach to introducing a wave function for the photon (following Good, 1957). This wave function ultimately turns out to be unsatisfactory because the probabilities derived from it do not always transform properly under Lorentz transformations. The fact that such a quantum interpretation of Maxwell's equations is unsatisfactory suggests that the electromagnetic field is more fundamental than the photon. Contents 1 Introduction2 arXiv:1902.01930v3 [quant-ph] 29 May 2019 2 The Weber Vector5 3 The Electromagnetic Field of a Single Photon7 4 The Photon Wave Function 11 5 Lorentz Transformations 14 6 Conclusion 22 1 1 Introduction Electromagnetism was a theory ahead of its time. It held within it the seeds of special relativity. Einstein discovered the special theory of relativity by studying the laws of electromagnetism, laws which were already relativistic.1 There are hints that electromagnetism may also have held within it the seeds of quantum mechanics, though quantum mechanics was not discovered by cultivating those seeds. -
Electromagnetic Field Theory
Lecture 4 Electromagnetic Field Theory “Our thoughts and feelings have Dr. G. V. Nagesh Kumar Professor and Head, Department of EEE, electromagnetic reality. JNTUA College of Engineering Pulivendula Manifest wisely.” Topics 1. Biot Savart’s Law 2. Ampere’s Law 3. Curl 2 Releation between Electric Field and Magnetic Field On 21 April 1820, Ørsted published his discovery that a compass needle was deflected from magnetic north by a nearby electric current, confirming a direct relationship between electricity and magnetism. 3 Magnetic Field 4 Magnetic Field 5 Direction of Magnetic Field 6 Direction of Magnetic Field 7 Properties of Magnetic Field 8 Magnetic Field Intensity • The quantitative measure of strongness or weakness of the magnetic field is given by magnetic field intensity or magnetic field strength. • It is denoted as H. It is a vector quantity • The magnetic field intensity at any point in the magnetic field is defined as the force experienced by a unit north pole of one Weber strength, when placed at that point. • The magnetic field intensity is measured in • Newtons/Weber (N/Wb) or • Amperes per metre (A/m) or • Ampere-turns / metre (AT/m). 9 Magnetic Field Density 10 Releation between B and H 11 Permeability 12 Biot Savart’s Law 13 Biot Savart’s Law 14 Biot Savart’s Law : Distributed Sources 15 Problem 16 Problem 17 H due to Infinitely Long Conductor 18 H due to Finite Long Conductor 19 H due to Finite Long Conductor 20 H at Centre of Circular Cylinder 21 H at Centre of Circular Cylinder 22 H on the axis of a Circular Loop -
(5G) Electromagnetic Field (EMF) Measurement and Maximum Power Extrapolation for Human Exposure Assessment
environments Article Experimental Procedure for Fifth Generation (5G) Electromagnetic Field (EMF) Measurement and Maximum Power Extrapolation for Human Exposure Assessment Daniele Franci 1,*, Stefano Coltellacci 1, Enrico Grillo 1, Settimio Pavoncello 1, Tommaso Aureli 1, Rossana Cintoli 1 and Marco Donald Migliore 2,3 1 ARPA Lazio (Agenzia per la Protezione Ambientale del Lazio), Via G. Saredo 52, 00172 Rome, Italy; [email protected] (S.C.); [email protected] (E.G.); [email protected] (S.P.); [email protected] (T.A.); [email protected] (R.C.) 2 DIEI (Dipartimento di Ingegeria Elettrica e dell’Informazione “Maurizio Scarano”)—University of Cassino and Southern Lazio, via G. Di Biasio 43,03043 Cassino, Italy; [email protected] 3 ICEmB(Inter-University National Research Center on Interactions Between Electromagnetic Fields and Biosystems), Via All’Opera Pia, 11 A, 16145 Genova GE, Italy * Correspondence: [email protected] Received: 30 January 2020; Accepted: 13 March 2020; Published: 17 March 2020 Abstract: The fifth generation (5G) technology has been conceived to cover multiple usage scenarios from enhanced mobile broadband to ultra-reliable low-latency communications (URLLC) to massive machine type communications. However, the implementation of this new technology is causing increasing concern over the possible impact on health and safety arising from exposure to electromagnetic field radiated by 5G systems, making imperative the development of accurate electromagnetic field (EMF) measurement techniques and protocols. Measurement techniques used to assess the compliance with EMF exposure limits are object to international regulation. The basic principle of the assessment is to measure the power received from a constant radio frequency source, typically a pilot signal, and to apply a proper extrapolation factor. -
Electro Magnetic Fields Lecture Notes B.Tech
ELECTRO MAGNETIC FIELDS LECTURE NOTES B.TECH (II YEAR – I SEM) (2019-20) Prepared by: M.KUMARA SWAMY., Asst.Prof Department of Electrical & Electronics Engineering MALLA REDDY COLLEGE OF ENGINEERING & TECHNOLOGY (Autonomous Institution – UGC, Govt. of India) Recognized under 2(f) and 12 (B) of UGC ACT 1956 (Affiliated to JNTUH, Hyderabad, Approved by AICTE - Accredited by NBA & NAAC – ‘A’ Grade - ISO 9001:2015 Certified) Maisammaguda, Dhulapally (Post Via. Kompally), Secunderabad – 500100, Telangana State, India ELECTRO MAGNETIC FIELDS Objectives: • To introduce the concepts of electric field, magnetic field. • Applications of electric and magnetic fields in the development of the theory for power transmission lines and electrical machines. UNIT – I Electrostatics: Electrostatic Fields – Coulomb’s Law – Electric Field Intensity (EFI) – EFI due to a line and a surface charge – Work done in moving a point charge in an electrostatic field – Electric Potential – Properties of potential function – Potential gradient – Gauss’s law – Application of Gauss’s Law – Maxwell’s first law, div ( D )=ρv – Laplace’s and Poison’s equations . Electric dipole – Dipole moment – potential and EFI due to an electric dipole. UNIT – II Dielectrics & Capacitance: Behavior of conductors in an electric field – Conductors and Insulators – Electric field inside a dielectric material – polarization – Dielectric – Conductor and Dielectric – Dielectric boundary conditions – Capacitance – Capacitance of parallel plates – spherical co‐axial capacitors. Current density – conduction and Convection current densities – Ohm’s law in point form – Equation of continuity UNIT – III Magneto Statics: Static magnetic fields – Biot‐Savart’s law – Magnetic field intensity (MFI) – MFI due to a straight current carrying filament – MFI due to circular, square and solenoid current Carrying wire – Relation between magnetic flux and magnetic flux density – Maxwell’s second Equation, div(B)=0, Ampere’s Law & Applications: Ampere’s circuital law and its applications viz. -
Displacement Current and Ampère's Circuital Law Ivan S
ELECTRICAL ENGINEERING Displacement current and Ampère's circuital law Ivan S. Bozev, Radoslav B. Borisov The existing literature about displacement current, although it is clearly defined, there are not enough publications clarifying its nature. Usually it is assumed that the electrical current is three types: conduction current, convection current and displacement current. In the first two cases we have directed movement of electrical charges, while in the third case we have time varying electric field. Most often for the displacement current is talking in capacitors. Taking account that charge carriers (electrons and charged particles occupy the negligible space in the surrounding them space, they can be regarded only as exciters of the displacement current that current fills all space and is superposition of the currents of the individual moving charges. For this purpose in the article analyzes the current configuration of lines in space around a moving charge. An analysis of the relationship between the excited magnetic field around the charge and the displacement current is made. It is shown excited magnetic flux density and excited the displacement current are linked by Ampere’s circuital law. ъ а аа я аъ а ъя (Ива . Бв, аав Б. Бв.) В я, я , я , яя . , я : , я я. я я, я я . я . К , я ( я я , я, я я я. З я я я. я я. , я я я я . 1. Introduction configurations of the electric field of moving charge are shown on Fig. 1 and Fig. 2. First figure represents The size of electronic components constantly delayed potentials of the electric field according to shrinks and the discrete nature of the matter is Liénard–Wiechert and this picture is not symmetrical becomming more obvious. -
Notes 4 Maxwell's Equations
ECE 3317 Applied Electromagnetic Waves Prof. David R. Jackson Fall 2020 Notes 4 Maxwell’s Equations Adapted from notes by Prof. Stuart A. Long 1 Overview Here we present an overview of Maxwell’s equations. A much more thorough discussion of Maxwell’s equations may be found in the class notes for ECE 3318: http://courses.egr.uh.edu/ECE/ECE3318 Notes 10: Electric Gauss’s law Notes 18: Faraday’s law Notes 28: Ampere’s law Notes 28: Magnetic Gauss law . D. Fleisch, A Student’s Guide to Maxwell’s Equations, Cambridge University Press, 2008. 2 Electromagnetic Fields Four vector quantities E electric field strength [Volt/meter] D electric flux density [Coulomb/meter2] H magnetic field strength [Amp/meter] B magnetic flux density [Weber/meter2] or [Tesla] Each are functions of space and time e.g. E(x,y,z,t) J electric current density [Amp/meter2] 3 ρv electric charge density [Coulomb/meter ] 3 MKS units length – meter [m] mass – kilogram [kg] time – second [sec] Some common prefixes and the power of ten each represent are listed below femto - f - 10-15 centi - c - 10-2 mega - M - 106 pico - p - 10-12 deci - d - 10-1 giga - G - 109 nano - n - 10-9 deka - da - 101 tera - T - 1012 micro - μ - 10-6 hecto - h - 102 peta - P - 1015 milli - m - 10-3 kilo - k - 103 4 Maxwell’s Equations (Time-varying, differential form) ∂B ∇×E =− ∂t ∂D ∇×HJ = + ∂t ∇⋅B =0 ∇⋅D =ρv 5 Maxwell James Clerk Maxwell (1831–1879) James Clerk Maxwell was a Scottish mathematician and theoretical physicist. -
THE CONCEPT of ELECTRON ACTIVITY and ITS RELATION to REDOX POTENTIALS in AQUEOUS GEOCHEMICAL SYSTEMS by Donald C
THE CONCEPT OF ELECTRON ACTIVITY AND ITS RELATION TO REDOX POTENTIALS IN AQUEOUS GEOCHEMICAL SYSTEMS by Donald C. Thorstenson U.S. GEOLOGICAL SURVEY Open-File Report 84 072 1984 UNITED STATES DEPARTMENT OF THE INTERIOR WILLIAM T. CLARK, Secretary GEOLOGICAL SURVEY Dallas L. Peck, Director For additional information Copies of this report may be write to: purchased from: Regional Research Hydrologist U.S. Geological Survey U.S. Geological Survey Western Distribution Branch Water Resources Division Open-File Services Section 432 National Center Box 25425, Federal Center Reston, Virginia 22092 Denver, Colorado 80225 ERRATA: (p. 1) 1. Equation (2), p. 3, should read: n 2.30RT 1 n 2.30RT , x = Ej? + _____ log__= E° + _____pH . (2) 2. Table 1, p. 6, entry 5, should read: In pure water, p e - 6.9; 3. Line 3, paragraph 3, p. 10 should read: As Fe^+ / aa \ is converted to Fe ( aa ) via equation (15) to 4. Equation (22), p. 13, should read: a n p - anya n+ e (aq) UA (aq) K = . (22) 5. Equation (38), p. 18, should read: F -log ae - = _______ Eh + . (38) ( acl) 2.303RT 2.303RT 6. Equation (52), p. 23, should read: ae- (aq) 7. Equation (53), p. 23, should read: pe s +6.9 and Eh s + 0.41 volt. (53) 8. Equation (54c), p. 23, should read: nu-'e ~ 10 -55.5 (aq) ERRATA: (p. 2) 9. The second line from the bottom, p. 28, should read: ....... (a state that has been maintained for * 105 years based on .... 10. The heading of Table 2, p. -
Chapter 1 ELECTROMAGNETICS of METALS
Chapter 1 ELECTROMAGNETICS OF METALS While the optical properties of metals are discussed in most textbooks on condensed matter physics, for convenience this chapter summarizes the most important facts and phenomena that form the basis for a study of surface plas- mon polaritons. Starting with a cursory review of Maxwell’s equations, we describe the electromagnetic response both of idealized and real metals over a wide frequency range, and introduce the fundamental excitation of the conduc- tion electron sea in bulk metals: volume plasmons. The chapter closes with a discussion of the electromagnetic energy density in dispersive media. 1.1 Maxwell’s Equations and Electromagnetic Wave Propagation The interaction of metals with electromagnetic fields can be firmly under- stood in a classical framework based on Maxwell’s equations. Even metallic nanostructures down to sizes on the order of a few nanometres can be described without a need to resort to quantum mechanics, since the high density of free carriers results in minute spacings of the electron energy levels compared to thermal excitations of energy kBT at room temperature. The optics of met- als described in this book thus falls within the realms of the classical theory. However, this does not prevent a rich and often unexpected variety of optical phenomena from occurring, due to the strong dependence of the optical prop- erties on frequency. As is well known from everyday experience, for frequencies up to the vis- ible part of the spectrum metals are highly reflective and do not allow elec- tromagnetic waves to propagate through them. Metals are thus traditionally employed as cladding layers for the construction of waveguides and resonators for electromagnetic radiation at microwave and far-infrared frequencies. -
European Information System on Electromagnetic Fields Exposure and Health Impacts
European Information System on Electromagnetic Fields Exposure and Health Impacts On behalf of DG SANCO Final Report February, 2005 EUROPEAN COMMISSION DIRECTORATE-GENERAL JOINT RESEARCH CENTRE Institute for Health and Consumer Protection Physical and Chemical Exposure Unit http://www.jrc.cec.eu.int/eis-emf EIS-EMF Project Final report Legal notice Neither the European Commission nor any person acting on behalf of the Commission is responsible for the use, which might be made of the following information. 1 EIS-EMF Project Final report 2 EIS-EMF Project Final report Organisation responsible of the project: European Commission, Joint Research Centre, Institute for Health and Consumer Protection, Physical and Chemical Exposure Unit, Ispra, Italy (JRC/IHCP/PCE). Project leader: Dr. Demosthenes Papameletiou, JRC/IHCP/PCE Sources of funding: DG Health and Consumer Protection (SANCO) and JRC/IHCP/PCE Sub-contractor: Seibersdorf Research, Austrian Research Centers Preparation of documents: All working drafts and this final report were prepared by the Joint Research Centre (Institute for Health and Consumer Protection, Physical and Chemical Exposure Unit), and with individual contributions and advice in the course of the work from members of the EIS-EMF Advisory Board and national supporting experts. The “Status report on national sources of RF exposure of the general population” was prepared together by Seiberdorf Research and the JRC/IHCP/PCE. Final drafting: Dr. Carlos del Pozo and Dr. Demosthenes Papameletiou, both at JRC/IHCP/PCE Advisory -
Data Collected and Reviewed Regarding a Health Study for People Living Near a Nuclear Facility
04-0138 Data Collected and Reviewed Regarding a Health Study for People Living Near a Nuclear Facility Report to the Minnesota Legislature 2004 Minnesota Department of Health February 9, 2004 MIN NE SOT A Commissioner's Office 85 East Seventh Place, Suite 400 P.O. Box 64882 St. Paul, MN 55164-0882 ~ ~ (651)215-1300 DEPARTMENT OF HEALTH www.hea1th.state.mn.us Data Collected and Reviewed Regarding a Health Study for People Living Near a Nuclear Facility February 9, 2004 For more information, contact: Environmental Health Division/Radiation Control Unit Minnesota Department of Health 1645 Energy Park Drive P.O. Box 64975 St. Paul, MN 55164-0975 Phone: (651) 643-2151 Fax: (651) 643-2152 TDD: (651) 215~0707 This report is produced as required by Minnesota Session Laws 2003, 1st Special Session, Chapter 11, Article 1, Sec. 5. As requested by Minnesota Statute 3.197: This report cost approximately $1,000 to prepare, including stafftime, printing and mailing expenses. Upon request, this material will be made available in an alternative format such as large print, Braille or cassette tape. Printed on recycled paper. Dear Interested Party: .The 2003 1st Special Session Chapter 11 Article 1, Sec. 5 requested that the Commissioner of Health "review data collected by the department, and in the context ofother relevant information developed by the National Institutes of Health and other entities, report to the legislature by January 1, 2004 on whether a further health study funded by the owner of the Prairie Island nuclear facility is necessary." Based on discussions with the author of this Section, the data reviewed focused on exposure to electric and magnetic fields. -
Metamaterials for Space Applications Final Report
Metamaterials for Space Applications Design of invisibility cloaks for reduced observability of objects Final Report Authors: F. Bilotti, S. Tricarico, L. Vegni Affiliation: University Roma Tre ESA Researcher(s): Jose M. Llorens and Luzi Bergamin Date: 20.7.2008 Contacts: Filiberto Bilotti Tel: +39.06.57337096 Fax: +39.06.57337026 e-mail: [email protected] Leopold Summerer Tel: +31(0)715655174 Fax: +31(0)715658018 e-mail: [email protected] Ariadna ID: 07/7001b Study Duration: 4 months Available on the ACT website http://www.esa.int/act Contract Number: 21263/07/NL/CB Contents Abstract ...................................................................................................................3 Objectives of the study .........................................................................................4 1 Design of Invisibility Cloaks at Microwaves ..............................................7 1.1 Cloak with ENZ materials at microwaves...................................................... 7 1.2 Cloak with MNZ materials at microwaves ................................................... 12 1.3 Full wave simulations of an ideal MNZ-ENZ cloak at microwaves.......... 15 1.4 Design of an MNZ-ENZ cloak at microwaves with magnetic inclusions 21 2 Design of a cloak with ENZ metamaterials at THz and/or optical frequencies............................................................................................................ 26 3 Reduction of the radiation pressure by optical cloaking ...................... 34 4 Conclusions..................................................................................................