Physics
Electromagnetism
Electromagnetism is a branch of physics that deals with the study of the electromagnetic force, which includes both electric and magnetic phenomena. It describes how electrically charged particles interact with each other and with magnetic fields. Electromagnetism is fundamental to understanding the behavior of charged particles, the functioning of electric motors, and the generation of electromagnetic waves.
Written by Perlego with AI-assistance
Related key terms
1 of 5
11 Key excerpts on "Electromagnetism"
No longer available |Learn more- (Author)
- 2014(Publication Date)
- Learning Press(Publisher)
____________________ WORLD TECHNOLOGIES ____________________ Chapter- 2 Electromagnetism Electromagnetism is one of the four fundamental interactions of nature. The other three are the strong interaction, the weak interaction and gravitation. Electromagnetism is the force that causes the interaction between electrically charged particles; the areas in which this happens are called electromagnetic fields. Electromagnetism is responsible for practically all the phenomena encountered in daily life, with the exception of gravity. Ordinary matter takes its form as a result of intermolecular forces between individual molecules in matter. Electromagnetism is also the force which holds electrons and protons together inside atoms, which are the building blocks of molecules. This governs the processes i nvolved in chemistry, which arise from interactions between the electrons orbiting atoms. Electromagnetism manifests as both electric fields and magnetic fields. Both fields are simply different aspects of Electromagnetism, and hence are intrinsically rela ted. Thus, a changing electric field generates a magnetic field; conversely a changing magnetic field generates an electric field. This effect is called electromagnetic induction, and is the basis of operation for electrical generators, induction motors, and transformers. Mathematically speaking, magnetic fields and electric fields are convertible with relative motion as a four vector. Electric fields are the cause of several common phenomena, such as electric potential (such as the voltage of a battery) and electric current (such as the flow of electricity through a flashlight). Magnetic fields are the cause of the force associated with magnets. In quantum electrodynamics, electromagnetic interactions between charged particles can be calculated using the method of Feynman diagrams, in which we picture messenger particles called virtual photons being exchanged between charged particles.
No longer available |Learn more- (Author)
- 2014(Publication Date)
- Academic Studio(Publisher)
Electromagnetism Electromagnetism is the force that acts between electrically charged particles. This phenomenon includes the electrostatic force acting between charged particles at rest, and the combined effect of electric and magnetic forces acting between charge particles moving relative to each other. Electromagnetism is infinite-ranged like gravity, but vastly stronger, and therefore describes almost all macroscopic phenomena of everyday experience, ranging from the impenetrability of solids, friction, rainbows, lightning, and all human-made devices using electric current, such as television, lasers, and computers. Electromagnetism funda-mentally determines all macroscopic, and many atomic level, properties of the chemical elements, including all chemical bonding. To get an idea of just how strong the electric force is, let us make a calculation. In a 1-gallon-U.S. (approx. 4 liter) jug of water, there are approximately 4,000 grams of water or of total electron charge. Thus, if we place two such jugs a meter apart, the electrons in one of the jugs repel those in the other jug with a force of This is larger than what the planet Earth would weigh if weighed on another Earth. The nuclei in one jug also repel those in the other with the same force. However, these repulsive forces are cancelled by the attraction of the electrons in jug A with the nuclei in jug B and the attraction of the nuclei in jug A with the electrons in jug B, resulting in no ________________________ WORLD TECHNOLOGIES ________________________ net force. The conclusion is clear: Electromagnetic forces are tremendously stronger than gravity but conspire to cancel out so perfectly that for large bodies gravity can dominate. Electrical and magnetic phenomena have been observed since ancient times, but it was only in the 19th century that it was discovered that electricity and magnetism are two aspects of the same fundamental interaction.
No longer available |Learn more- (Author)
- 2014(Publication Date)
- Academic Studio(Publisher)
____________________ WORLD TECHNOLOGIES ____________________ Chapter- 11 Electromagnetism Electromagnetism is one of the four fundamental interactions of nature. The other three are the strong interaction, the weak interaction and gravitation. Electromagnetism is the force that causes the interaction between electrically charged particles; the areas in which this happens are called electromagnetic fields. Electromagnetism is responsible for practically all the phenomena encountered in daily life, with the exception of gravity. Ordinary matter takes its form as a result of intermolecular forces between individual molecules in matter. Electromagnetism is also the force which holds electrons and protons together inside atoms, which are the building blocks of molecules. This governs the processes involved in chemistry, which arise from interactions between the electrons orbiting atoms. Electromagnetism manifests as both electric fields and magnetic fields. Both fields are simply different aspects of Electromagnetism, and hence are intrinsically related. Thus, a changing electric field generates a magnetic field; conversely a changing magnetic field generates an electric field. This effect is called electromagnetic induction, and is the basis of operation for electrical generators, induction motors, and transformers. Mathematically speaking, magnetic fields and electric fields are convertible with relative motion as a four vector. Electric fields are the cause of several common phenomena, such as electric potential (such as the voltage of a battery) and electric current (such as the flow of electricity through a flashlight). Magnetic fields are the cause of the force associated with magnets. In quantum electrodynamics, electromagnetic interactions between charged particles can be calculated using the method of Feynman diagrams, in which we picture messenger particles called virtual photons being exchanged between charged particles.
No longer available |Learn more- (Author)
- 2014(Publication Date)
- Academic Studio(Publisher)
________________________ WORLD TECHNOLOGIES ________________________ Chapter 10 Electromagnetism Electromagnetism is one of the four fundamental interactions of nature. The other three are the strong interaction, the weak interaction and gravitation. Electromagnetism is the force that causes the interaction between electrically charged particles; the areas in which this happens are called electromagnetic fields. Electromagnetism is responsible for practically all the phenomena encountered in daily life, with the exception of gravity. Ordinary matter takes its form as a result of intermolecular forces between individual molecules in matter. Electromagnetism is also the force which holds electrons and protons together inside atoms, which are the building blocks of molecules. This governs the processes involved in chemistry, which arise from interactions between the electrons orbiting atoms. Electromagnetism manifests as both electric fields and magnetic fields. Both fields are simply different aspects of Electromagnetism, and hence are intrinsically related. Thus, a changing electric field generates a magnetic field; conversely a changing magnetic field generates an electric field. This effect is called electromagnetic induction, and is the basis of operation for electrical generators, induction motors, and transformers. Mathematically speaking, magnetic fields and electric fields are convertible with relative motion as a four vector. Electric fields are the cause of several common phenomena, such as electric potential (such as the voltage of a battery) and electric current (such as the flow of electricity through a flashlight). Magnetic fields are the cause of the force associated with magnets. In quantum electrodynamics, electromagnetic interactions between charged particles can be calculated using the method of Feynman diagrams, in which we picture messenger particles called virtual photons being exchanged between charged particles.
No longer available |Learn more- (Author)
- 2014(Publication Date)
- Library Press(Publisher)
________________________ WORLD TECHNOLOGIES ________________________ Chapter- 2 Electromagnetism Electromagnetism is one of the four fundamental interactions of nature. The other three are the strong interaction, the weak interaction and gravitation. Electromagnetism is the force that causes the interaction between electrically charged particles; the areas in which this happens are called electromagnetic fields. Electromagnetism is responsible for practically all the phenomena encountered in daily life, with the exception of gravity. Ordinary matter takes its form as a result of inter-molecular forces between individual molecules in matter. Electromagnetism is also the force which holds electrons and protons together inside atoms, which are the building blocks of molecules. This governs the processes involved in chemistry, which arise from interactions between the electrons orbiting atoms. Electromagnetism manifests as both electric fields and magnetic fields. Both fields are simply different aspects of Electromagnetism, and hence are intrinsically related. Thus, a changing electric field generates a magnetic field; conversely a changing magnetic field generates an electric field. This effect is called electromagnetic induction, and is the basis of operation for electrical generators, induction motors, and transformers. Mathematically speaking, magnetic fields and electric fields are convertible with relative motion as a four vector. Electric fields are the cause of several common phenomena, such as electric potential (such as the voltage of a battery) and electric current (such as the flow of electricity through a flashlight). Magnetic fields are the cause of the force associated with magnets. In quantum electrodynamics, electromagnetic interactions between charged particles can be calculated using the method of Feynman diagrams, in which we picture messenger particles called virtual photons being exchanged between charged particles.
No longer available |Learn more- (Author)
- 2014(Publication Date)
- Learning Press(Publisher)
________________________ WORLD TECHNOLOGIES ________________________ Chapter- 3 Electromagnetism Electromagnetism is one of the four fundamental interactions of nature. The other three are the strong interaction, the weak interaction and gravitation. Electromagnetism is the force that causes the interaction between electrically charged particles; the areas in which this happens are called electromagnetic fields. Electromagnetism is responsible for practically all the phenomena encountered in daily life, with the exception of gravity. Ordinary matter takes its form as a result of intermolecular forces between individual molecules in matter. Electromagnetism is also the force which holds electrons and protons together inside atoms, which are the building blocks of molecules. This governs the processes involved in chemistry, which arise from interactions between the electrons orbiting atoms. Electromagnetism manifests as both electric fields and magnetic fields. Both fields are simply different aspects of Electromagnetism, and hence are intrinsically related. Thus, a changing electric field generates a magnetic field; conversely a changing magnetic field generates an electric field. This effect is called electromagnetic induction, and is the basis of operation for electrical generators, induction motors, and transformers. Mathematically speaking, magnetic fields and electric fields are convertible with relative motion as a four vector. Electric fields are the cause of several common phenomena, such as electric potential (such as the voltage of a battery) and electric current (such as the flow of electricity through a flashlight). Magnetic fields are the cause of the force associated with magnets. In quantum electrodynamics, electromagnetic interactions between charged particles can be calculated using the method of Feynman diagrams, in which we picture messenger particles called virtual photons being exchanged between charged particles.
- Swapan K Saha(Author)
- 2007(Publication Date)
- World Scientific(Publisher)
Chapter 1 Introduction to electromagnetic theory 1.1 Introduction Electromagnetism is a fundamental physical phenomena that is basic to many areas science and technology. This phenomenon is due to the interac-tion, called electromagnetic interaction, of electric and magnetic fields with the constituent particles of matter. This interaction is physically described in terms of electromagnetic fields, characterized by the electric field vector, E and the magnetic induction, B . These field vectors are generally time-dependent as they are determined by the positions of the electric charges and their motions (currents) in a medium in which the electromagnetic field exists. The fields E and B are directly correlated by Amp` ere-Maxwell and Faraday-Henry laws that satisfy the requirements of special relativity. The time-dependent relations between the time-dependent vectors in these laws and Gauss’ laws for electric and magnetic fields are given by Maxwell’s equations that form the the basis of electromagnetic theory. The electric charge and current distributions enter into these equations and are called the sources of the electromagnetic field, because if they are given Maxwell’s equations may be solved for E and B under appropriate boundary conditions. 1.2 Maxwell’s equations In order to describe the effect of the electromagnetic field on matter, it is necessary to make use, apart from E and B , of a set another three field vectors, viz., the magnetic vector, H , the electric displacement vector, D , and the electric current density, J . The four Maxwell’s equations may be written either in integral form or in differential form. In differential form, 1 2 Diffraction-limited imaging with large and moderate telescopes the Maxwell’s equations are expressed as, ∇ × E ( r, t ) = -1 c • ∂B ( r, t ) ∂t ‚ , (1.1) ∇ × H ( r, t ) = 1 c • 4 πJ ( r, t ) + ∂D ( r, t ) ∂t ‚ , (1.2) ∇ · D ( r, t ) = 4 πρ ( r, t ) and (1.3) ∇ · B ( r, t ) = 0 .
eBook - PDF- Graham Woan(Author)
- 2000(Publication Date)
- Cambridge University Press(Publisher)
7 Chapter 7 Electromagnetism 7.1 Introduction The electromagnetic force is central to nearly every physical process around us and is a major component of classical physics. In fact, the development of electromagnetic theory in the nineteenth century gave us much mathematical machinery that we now apply quite generally in other fields, including potential theory, vector calculus, and the ideas of divergence and curl. It is therefore not surprising that this section deals with a large array of physical quantities and their relationships. As usual, SI units are assumed throughout. In the past Electromagnetism has suffered from the use of a variety of systems of units, including the cgs system in both its electrostatic (esu) and electromagnetic (emu) forms. The fog has now all but cleared, but some specialised areas of research still cling to these historical measures. Readers are advised to consult the section on unit conversion if they come across such exotica in the literature. Equations cast in the rationalised units of SI can be readily converted to the once common Gaussian (unrationalised) units by using the following symbol transformations: Equation conversion: SI to Gaussian units 0 → 1 / (4 π ) µ 0 → 4 π/c 2 B → B /c χ E → 4 πχ E χ H → 4 πχ H H → c H / (4 π ) A → A /c M → c M D → D / (4 π ) The quantities ρ , J , E , φ , σ , P , r , and µ r are all unchanged.
eBook - PDFElectromagnetics through the Finite Element Method
A Simplified Approach Using Maxwell's Equations
- José Roberto Cardoso(Author)
- 2016(Publication Date)
- CRC Press(Publisher)
2 Fundamentals of Electromagnetism 2.1 SOURCES OF ELECTROMAGNETIC FIELD Richard Feynman was one of the greatest scientists of the twentieth century, who won the Nobel prize in physics and the author of one of the most famous works on fundamental physics (Lectures on Physics ) [16]. He suggested in his book that if civilizations became extinct leaving you as the only human being in contact with a new civilization being born and if you could communicate through one sentence during that time, then that sentence should bear the most important information from humanity. This is the concept behind atom formation, where a set of negative elec- tric charges surround a set of positive charges indefnitely. This information, which is considered to be the frst mode of interaction in the feld of science, marked the beginning of evolution. The concept of electric charge is rooted deep in our knowledge, and only after a closer involvement with science was established, we started to understand its origin through atoms without doubting this concept. We were also able to understand the distribution of isolated electric charges in space thereby understanding several physi- cal phenomenon, such as Coulomb’s law. On the other hand, the human body, at a microscopic level, essentially consists of electric charges. Feynman also asserted that if an unbalance of only 10% is found between positive and negative electric charges in our body, the intensity of force between you and the next person, would be suffcient to move the entire Earth! These electric charges are responsible for the generation of electromagnetic felds. Their state of animation is also relevant; if electric charges are stationary or moving (constituting an electric current), their actions over electromagnetic felds are com- pletely different, as we are going to discuss next. Actions of electric charges in applied Electromagnetism are based on the macroscopic conception of the phenomenon.
eBook - PDFEngineering Electromagnetics
Pergamon Unified Engineering Series
- David T. Thomas, Thomas F. Irvine, James P. Hartnett, William F. Hughes(Authors)
- 2013(Publication Date)
- Pergamon(Publisher)
2 The Physical Basis of Electromagnetics INTRODUCTION AND HISTORY All that we know of electricity and magnetism is due to the experiments and observations made by man. While there have been theoretical breakthroughs in electromagnetics as in every science, without empirical laws to work from no theory could have been accomplished. In the end, it is only after experimental verification that a theory is really accepted. This chapter will present the funda-mentals of electromagnetics in the form of empirical laws which have stood the test of time and doubt and extensive experimental verification. The history of electricity and magnetism as we call it today begins in antiquity. If we discount those cave dwellers who simply observed and marvelled at light-ning, the ancient Greeks were the first to observe and record electromagnetic phenomena and speculate about the causes. The Greeks, for example, knew of the lodestone or permanent magnet, and Plato wrote that the powers of attraction between lodestones could be imparted to iron rings which would then attract each other. Aristotle spoke of the nature of light, as did Euclid and Ptolemy. However it was not until the eighteenth century that substantive laws began to evolve. Historically the simpler laws or equations were discovered first. Couloumbs Law was first established by Cavendish in experiments as early as 1773, but Cavendish unfortunately did not publicize his findings. Couloumb in 1785 published his celebrated First Memoir on Electricity and Magnetism in which appeared the law of attraction (or repulsion) of two point charges, Q x and Q 2 , where r 12 = the distance between the two charges, r 12 = the unit vector directed along the line connecting the two charges, K = a constant. 37 38 The Physical Basis of Electromagnetics This inverse square law for the force between two charges caused many refer-ences to the analogous inverse square law of gravity, a subject well understood in those days.
eBook - PDF- Richard L. Myers(Author)
- 2005(Publication Date)
- Greenwood(Publisher)
Gilbert was a proponent of Copernicus' heliocentric model, and his ideas were very influential on other scien- tists. He was highly praised by Galileo and is often called the father of modern electric- ity and magnetism. Until the start of the nineteenth cen- tury, magnetism was considered a distinct force separate from electricity. In 1820, Hans Christian Oersted (1777-1851), while performing a demonstration on the heating effects of electric current, observed that a nearby compass needle was deflected when current flowed through his circuit. Oersted didn't have an explanation for the compass' deflection, but continued to do experiments on the effect of current on a compass needle. Others such as Michael Faraday, Andre- Marie Ampere, and James Clerk Maxwell 256 Magnetism and Electromagnetism (1831-1879) demonstrated that electricity and magnetism were related and were in fact different components of the combined phenomenon of Electromagnetism. This chapter will build on the material of chapter 13 by first examining the general concept of magnetism. We will then explore the unique relationship between electricity and magnetism and how these combine to produce Electromagnetism. The technologi- cal aspects of magnetism will be addressed by examining practical uses of electromag- netism. Among the numerous common devices based on electromagnetic principles are motors, generators, and transformers. A number of the concepts of electromagne- tism will be illustrated by examining these applications and other applications. The Magnetic Field and Source of Magnetism Oersted's initial observation and subse- quent work by him and others demonstrated that an electric current creates a magnetic field. The field concept was discussed in chapter 13 on electricity. A charged object alters the space around it, and this altered space can be represented with lines of force that map the electric field.
Index pages curate the most relevant extracts from our library of academic textbooks. They’ve been created using an in-house natural language model (NLM), each adding context and meaning to key research topics.
