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For other senses of this word, see magnetism (disambiguation).
Electromagnetism
Electricity · Magnetism
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In physics, magnetism is one of the phenomena by which materials exert attractive or repulsive forces on other materials. Electromagnetism is the Physics of the Electromagnetic field: a field which exerts a Force on particles that possess the property of Physics (Greek Physis - φύσις in everyday terms is the Science of Matter and its motion. A phenomenon (from Greek φαινόμενoν, pl φαινόμενα - phenomena) is any observable occurrence Materials are physical Substances used as inputs to production or Manufacturing. In Physics, a force is whatever can cause an object with Mass to Accelerate. Materials are physical Substances used as inputs to production or Manufacturing. Some well-known materials that exhibit easily detectable magnetic properties (called magnets) are nickel, iron, cobalt, and their alloys; however, all materials are influenced to greater or lesser degree by the presence of a magnetic field. A magnet (from Greek grc μαγνήτης λίθος " Magnesian stone" is a material or object that produces a Magnetic field. Nickel (ˈnɪkəl is a metallic Chemical element with the symbol Ni and Atomic number 28 Iron (ˈаɪɚn is a Chemical element with the symbol Fe (ferrum and Atomic number 26 Cobalt (ˈkoʊbɒlt is a hard lustrous silver-grey Metal, a Chemical element with symbol Co. An alloy is a Solid solution or Homogeneous mixture of two or more elements, at least one of which is a Metal, which itself has In Physics, a magnetic field is a Vector field that permeates space and which can exert a magnetic force on moving Electric charges

Magnetism also has other manifestations in physics, particularly as one of the two components of electromagnetic waves such as light. Electromagnetic radiation takes the form of self-propagating Waves in a Vacuum or in Matter. Light, or visible light, is Electromagnetic radiation of a Wavelength that is visible to the Human eye (about 400–700

Contents

History

Aristotle attributes the first of what could be called a scientific discussion on magnetism to Thales, who lived from about 625 BC to about 545 BC. Aristotle (Greek Aristotélēs) (384 BC – 322 BC was a Greek philosopher a student of Plato and teacher of Alexander the Great. Thales of Miletus According to Bertrand Russell, "Philosophy begins with Thales [1] In China, the earliest literary reference to magnetism lies in a 4th century BC book called Book of the Devil Valley Master (鬼谷子): "The lodestone makes iron come or it attracts it. Lodestone or loadstone refers to either Magnetite, a Magnetic Mineral form of iron(II, Iron(III oxide Iron (ˈаɪɚn is a Chemical element with the symbol Fe (ferrum and Atomic number 26 "[2] The earliest mention of the attraction of a needle appears in a work composed between 20 and 100 AD (Louen-heng): "A lodestone attracts a needle. "[3] The ancient Chinese scientist Shen Kuo (1031-1095) was the first person to write of the magnetic needle compass and that it improved the accuracy of navigation by employing the astronomical concept of true north (Dream Pool Essays, 1088 AD), and by the 12th century the Chinese were known to use the lodestone compass for navigation. China ( Wade-Giles ( Mandarin) Chung¹kuo² is a cultural region, an ancient Civilization, and depending on perspective a National Shen Kuo or Shen Kua ( (1031&ndash1095 style name Cunzhong and pseudonym Mengqi Weng, was a Polymathic Chinese Astronomy (from the Greek words astron (ἄστρον "star" and nomos (νόμος "law" is the scientific study noted by the Chinese Polymath Shen Kuo in the 11th century and possibly the egyptians over 6 millenia ago The Dream Pool Essays ( Pinyin: Meng Xi Bi Tan; Wade-Giles: Meng Ch'i Pi T'an Chinese: 夢溪筆談／梦溪笔谈 A compass, magnetic compass or mariner's compass is a navigational instrument for determining direction relative to the earth's Magnetic poles It consists Alexander Neckham, by 1187, was the first in Europe to describe the compass and its use for navigation. Alexander ( of) Neckam ( 8 September 1157 &ndash 1217 was an English scholar and teacher In 1269 Peter Peregrinus de Maricourt wrote the Epistola de magnete, the first extant treatise describing the properties of magnets. Peter of Maricourt ( Peter Peregrinus of Maricourt; French Pierre de Maricourt; Latin Petrus Peregrinus de Maricourt) (fl

In 1600 William Gilbert published his De Magnete, Magneticisque Corporibus, et de Magno Magnete Tellure (On the Magnet and Magnetic Bodies, and on the Great Magnet the Earth). William Gilbert, also known as Gilbard ( Colchester, England, May 24, 1544 &ndash London, England, November 30 De Magnete Magneticisque Corporibus et de Magno Magnete Tellure ( On the Magnet and Magnetic Bodies and on That Great Magnet the Earth) is a scientific In this work he describes many of his experiments with his model earth called the terrella. A terrella (meaning "little earth" is a small magnetised model ball representing the Earth, that is thought to have been invented by Englishman From his experiments, he concluded that the Earth was itself magnetic and that this was the reason compasses pointed north (previously, some believed that it was the pole star (Polaris) or a large magnetic island on the north pole that attracted the compass). Earth 's magnetic field (and the surface magnetic field) is approximately a Magnetic dipole, with one pole near the North pole (see In Physics, magnetism is one of the Phenomena by which Materials exert attractive or repulsive Forces on other Materials. A compass, magnetic compass or mariner's compass is a navigational instrument for determining direction relative to the earth's Magnetic poles It consists Polaris (α UMi / α Ursae Minoris / Alpha Ursae Minoris commonly North(ern Star or Pole Star, and sometimes Lodestar

An understanding of the relationship between electricity and magnetism began in 1819 with work by Hans Christian Oersted, a professor at the University of Copenhagen, who discovered more or less by accident that an electric current could influence a compass needle. This landmark experiment is known as Oersted's Experiment. Several other experiments followed, with André-Marie Ampère, Carl Friedrich Gauss, Michael Faraday, and others finding further links between magnetism and electricity. André-Marie Ampère (20 January 1775 &ndash 10 June 1836 was a French Physicist and Mathematician who is generally credited as one of the main discoverers Johann Carl Friedrich Gauss (ˈɡaʊs, Gauß Carolus Fridericus Gauss ( 30 April 1777 – 23 February 1855) was a German Michael Faraday, FRS ( September 22 1791 – August 25 1867) was an English James Clerk Maxwell synthesized and expanded these insights into Maxwell's equations, unifying electricity, magnetism, and optics into the field of electromagnetism. James Clerk Maxwell (13 June 1831 &ndash 5 November 1879 was a Scottish mathematician and theoretical physicist. In Classical electromagnetism, Maxwell's equations are a set of four Partial differential equations that describe the properties of the electric Electromagnetism is the Physics of the Electromagnetic field: a field which exerts a Force on particles that possess the property of In 1905, Einstein used these laws in motivating his theory of special relativity[4], requiring that the laws held true in all inertial reference frames. Albert Einstein ( German: ˈalbɐt ˈaɪ̯nʃtaɪ̯n; English: ˈælbɝt ˈaɪnstaɪn (14 March 1879 – 18 April 1955 was a German -born theoretical Special relativity (SR (also known as the special theory of relativity or STR) is the Physical theory of Measurement in Inertial In Physics, an inertial frame of reference is a Frame of reference which belongs to a set of frames in which Physical laws hold in the same and simplest

Electromagnetism has continued to develop into the twentieth century, being incorporated into the more fundamental theories of gauge theory, quantum electrodynamics, electroweak theory, and finally the standard model. Gauge theory is a peculiar Quantum field theory where the Lagrangian is invariant under certain transformations Quantum electrodynamics ( QED) is a relativistic Quantum field theory of Electrodynamics. In Particle physics, the electroweak interaction is the unified description of two of the four Fundamental interactions of nature Electromagnetism and the The Standard Model of Particle physics is a theory that describes three of the four known Fundamental interactions together with the Elementary particles

Physics of magnetism

Magnets and magnetic materials

Main article: Magnet

Every electron, by its nature, is a small magnet (see Electron magnetic dipole moment). A magnet (from Greek grc μαγνήτης λίθος " Magnesian stone" is a material or object that produces a Magnetic field. The electron is a fundamental Subatomic particle that was identified and assigned the negative charge in 1897 by J In Atomic physics, the magnetic dipole moment of an Electron is caused by its intrinsic property of spin within a magnetic field Ordinarily, the countless electrons in a material are randomly oriented in different directions, leaving no effect on average, but in a bar magnet the electrons are aligned in the same direction, so they act cooperatively, creating a net magnetic field.

In addition to the electron's intrinsic magnetic field, there is sometimes an additional magnetic field that results from the electron's orbital motion about the nucleus. The article on Magnetism states that the physical cause of an atomic magnetic dipole (or moment is two kinds of movement of electrons This effect is analogous to how a current-carrying loop of wire generates a magnetic field (see Magnetic dipole). In physics there are two kinds of dipoles ( Hellènic: di(s- = two- and pòla = pivot hinge An electric dipole is a Again, ordinarily, the motion of the electrons is such that there is no average field from the material, but in certain conditions, the motion can line up so as to produce a measurable total field.

The overall magnetic behavior of a material can vary widely, depending on the structure of the material, and particularly on its electron configuration. In Atomic physics and Quantum chemistry, electron configuration is the arrangement of Electrons in an Atom, Molecule, or other Several forms of magnetic behavior have been observed in different materials, including:

Magnetism, electricity, and special relativity

Main article: Classical electromagnetism and special relativity

As a consequence of Einstein's theory of special relativity, electricity and magnetism are understood to be fundamentally interlinked. Diamagnetism is the property of an object which causes it to create a magnetic field in opposition of an externally applied Magnetic field, thus causing a repulsive effect Paramagnetism is a form of magnetism which occurs only in the presence of an externally applied magnetic field A single-molecule magnet or SMM is an object that is composed of Molecules each of which behaves as an individual superparamagnet. Ferromagnetism is the basic mechanism by which certain materials (such as Iron) form Permanent magnets and/or exhibit strong interactions with Magnets it In materials that exhibit antiferromagnetism, the magnetic moments of atoms or molecules usuallyrelated to the spins of Electrons align in a regular pattern with neighboring In Physics, a ferrimagnetic material is one in which the Magnetic moment of the atoms on different sublattices are opposed as in Antiferromagnetism; however Metamagnetism is a blanket term used loosely in physics to describe a sudden (often dramatic increase in the Magnetization of a material with a small change in an externally A spin glass is a disordered material exhibiting high magnetic frustration. Superparamagnetism is a form of Magnetism. A superparamagnetic material is composed of small Ferromagnetic clusters (e The theory of Special relativity plays an important role in the modern theory of Classical electromagnetism. Special relativity (SR (also known as the special theory of relativity or STR) is the Physical theory of Measurement in Inertial Both magnetism lacking electricity, and electricity without magnetism, are inconsistent with special relativity, due to such effects as length contraction, time dilation, and the fact that the magnetic force is velocity-dependent. Length contraction, according to Hendrik Lorentz, is the physical phenomenon of a decrease in Length detected by an observer in objects that travel at any non-zero This article discusses a concept in physics For the concept in sociology see Time displacement. In Physics, a magnetic field is a Vector field that permeates space and which can exert a magnetic force on moving Electric charges However, when both electricity and magnetism are taken into account, the resulting theory (electromagnetism) is fully consistent with special relativity[5][6]. Electromagnetism is the Physics of the Electromagnetic field: a field which exerts a Force on particles that possess the property of In particular, a phenomenon that appears purely electric to one observer may be purely magnetic to another, or more generally the relative contributions of electricity and magnetism are dependent on the frame of reference. Thus, special relativity "mixes" electricity and magnetism into a single, inseparable phenomenon called electromagnetism (analogously to how special relativity "mixes" space and time into spacetime). SpaceTime is a patent-pending three dimensional graphical user interface that allows end users to search their content such as Google Google Images Yahoo! YouTube eBay Amazon and RSS

Magnetic fields and forces

Magnetic lines of force of a bar magnet shown by iron filings on paper
Magnetic lines of force of a bar magnet shown by iron filings on paper
Main article: Magnetic field

The phenomenon of magnetism is "mediated" by the magnetic field -- i. In Physics, a magnetic field is a Vector field that permeates space and which can exert a magnetic force on moving Electric charges In Physics, a magnetic field is a Vector field that permeates space and which can exert a magnetic force on moving Electric charges e. , an electric current or magnetic dipole creates a magnetic field, and that field, in turn, imparts magnetic forces on other particles that are in the fields.

To an excellent approximation (but ignoring some quantum effects---see quantum electrodynamics), Maxwell's equations (which simplify to the Biot-Savart law in the case of steady currents) describe the origin and behavior of the fields that govern these forces. Quantum electrodynamics ( QED) is a relativistic Quantum field theory of Electrodynamics. In Classical electromagnetism, Maxwell's equations are a set of four Partial differential equations that describe the properties of the electric The Biot–Savart Law is an equation in electromagnetism that describes the Magnetic field B generated by an Electric current. Therefore magnetism is seen whenever electrically charged particles are in motion---for example, from movement of electrons in an electric current, or in certain cases from the orbital motion of electrons around an atom's nucleus. Electric charge is a fundamental conserved property of some Subatomic particles which determines their Electromagnetic interaction. In Physics, motion means a constant change in the location of a body The electron is a fundamental Subatomic particle that was identified and assigned the negative charge in 1897 by J Electric current is the flow (movement of Electric charge. The SI unit of electric current is the Ampere. The article on Magnetism states that the physical cause of an atomic magnetic dipole (or moment is two kinds of movement of electrons They also arise from "intrinsic" magnetic dipoles arising from quantum effects, i. In physics there are two kinds of dipoles ( Hellènic: di(s- = two- and pòla = pivot hinge An electric dipole is a e. from quantum-mechanical spin. In Quantum mechanics, spin is a fundamental property of atomic nuclei, Hadrons and Elementary particles For particles with non-zero spin

The same situations which create magnetic fields (charge moving in a current or in an atom, and intrinsic magnetic dipoles) are also the situations in which a magnetic field has an effect, creating a force. In Physics, a force is whatever can cause an object with Mass to Accelerate. Following is the formula for moving charge; for the forces on an intrinsic dipole, see magnetic dipole. In physics there are two kinds of dipoles ( Hellènic: di(s- = two- and pòla = pivot hinge An electric dipole is a

When a charged particle moves through a magnetic field B, it feels a force F given by the cross product:

\vec{F} = q \vec{v} \times \vec{B}

where q\, is the electric charge of the particle, \vec{v} \, is the velocity vector of the particle, and \vec{B} \, is the magnetic field. In Physics, a magnetic field is a Vector field that permeates space and which can exert a magnetic force on moving Electric charges In Physics, a force is whatever can cause an object with Mass to Accelerate. In Mathematics, the cross product is a Binary operation on two vectors in a three-dimensional Euclidean space that results in another vector which Electric charge is a fundamental conserved property of some Subatomic particles which determines their Electromagnetic interaction. In Physics, velocity is defined as the rate of change of Position. In Physics, a magnetic field is a Vector field that permeates space and which can exert a magnetic force on moving Electric charges Because this is a cross product, the force is perpendicular to both the motion of the particle and the magnetic field. In Geometry, two lines or planes (or a line and a plane are considered perpendicular (or orthogonal) to each other if they form congruent It follows that the magnetic force does no work on the particle; it may change the direction of the particle's movement, but it cannot cause it to speed up or slow down. In Physics, mechanical work is the amount of Energy transferred by a Force. The magnitude of the force is

F = q v B \sin\theta\,

where \theta \, is the angle between the \vec{v} \, and \vec{B} \, vectors.

One tool for determining the direction of the velocity vector of a moving charge, the magnetic field, and the force exerted is labeling the index finger "V", the middle finger "B", and the thumb "F" with your right hand. In Physics, velocity is defined as the rate of change of Position. The second Digit of a human Hand is also referred to as the index finger, pointer finger, forefinger, trigger finger, digitus The middle finger (or the long finger) is the third digit of the human Hand and usually the longest Finger, located between the Index finger The thumb is the medial -most digit of the hand The English adjective for thumb is pollical When making a gun-like configuration (with the middle finger crossing under the index finger), the fingers represent the velocity vector, magnetic field vector, and force vector, respectively. See also right hand rule. For the related yet different principle relating to electromagnetic coils see Right hand grip rule.

Lenz's law gives the direction of the induced electromotive force (emf) and current resulting from electromagnetic induction. Lenz's law (ˈlɛntsɨz ˌlɔː gives the direction of the induced Electromotive force (emf and current resulting from Electromagnetic induction. German physicist Heinrich Lenz formulated it in 1834.

Magnetic dipoles

Main article: Magnetic dipole

A very common source of magnetic field shown in nature is a dipole, with a "South pole" and a "North pole"; terms dating back to the use of magnets as compasses, interacting with the Earth's magnetic field to indicate North and South on the globe. In physics there are two kinds of dipoles ( Hellènic: di(s- = two- and pòla = pivot hinge An electric dipole is a In Physics, a magnetic field is a Vector field that permeates space and which can exert a magnetic force on moving Electric charges In physics there are two kinds of dipoles ( Hellènic: di(s- = two- and pòla = pivot hinge An electric dipole is a The South Pole, also known as the Geographic South Pole or Terrestrial South Pole, is the southernmost point on the surface of the Earth. The North Pole, also known as the Geographic North Pole or Terrestrial North Pole, is subject to the caveats explained below defined as the point in the northern A compass, magnetic compass or mariner's compass is a navigational instrument for determining direction relative to the earth's Magnetic poles It consists Earth 's magnetic field (and the surface magnetic field) is approximately a Magnetic dipole, with one pole near the North pole (see A globe is a three- Dimensional scale model of Earth ( terrestrial globe) or other spheroid celestial body such as a planet star or moon Since opposite ends of magnets are attracted, the north pole of a magnet is attracted to the south pole of another magnet. Interestingly, this concept of opposite polaraties attracting wasn't used in the naming convention for the earth's magnetic field, so the earth's magnetic north pole (in Canada) attracts the magnetic north pole of a compass see North Magnetic Pole. The Earth's North Magnetic Pole is the wandering point on the Earth's surface at which the Earth's magnetic field points vertically downwards (i

A magnetic field contains energy, and physical systems move toward configurations with lower energy. In Physics and other Sciences energy (from the Greek grc ἐνέργεια - Energeia, "activity operation" from grc ἐνεργός Therefore, when placed in a magnetic field, a magnetic dipole tends to align itself in opposed polarity to that field, thereby canceling the net field strength as much as possible and lowering the energy stored in that field to a minimum. For instance, two identical bar magnets placed side-to-side normally line up North to South, resulting in a much smaller net magnetic field, and resist any attempts to reorient them to point in the same direction. The energy required to reorient them in that configuration is then stored in the resulting magnetic field, which is double the strength of the field of each individual magnet. (This is, of course, why a magnet used as a compass interacts with the Earth's magnetic field to indicate North and South).

An alternative, equivalent formulation, which is often easier to apply but perhaps offers less insight, is that a magnetic dipole in a magnetic field experiences a torque and a force which can be expressed in terms of the field and the strength of the dipole (i. A torque (τ in Physics, also called a moment (of force is a pseudo- vector that measures the tendency of a force to rotate an object about In Physics, a force is whatever can cause an object with Mass to Accelerate. e. , its magnetic dipole moment). In Physics, Astronomy, Chemistry, and Electrical engineering, the term magnetic moment of a system (such as a loop of Electric current For these equations, see magnetic dipole. In physics there are two kinds of dipoles ( Hellènic: di(s- = two- and pòla = pivot hinge An electric dipole is a

Magnetic monopoles

Main article: Magnetic monopole

Since a bar magnet gets its ferromagnetism from electrons distributed evenly throughout the bar, when a bar magnet is cut in half, each of the resulting pieces is a smaller bar magnet. In Physics, a magnetic monopole is a hypothetical particle that is a Magnet with only one pole (see Maxwell's equations for more on magnetic Even though a magnet is said to have a north pole and a south pole, these two poles cannot be separated from each other. A monopole — if such a thing exists — would be a new and fundamentally different kind of magnetic object. It would act as an isolated north pole, not attached to a south pole, or vice versa. Monopoles would carry "magnetic charge" analogous to electric charge. Despite systematic searches since 1931, as of 2006, they have never been observed, and could very well not exist. Year 2006 ( MMVI) was a Common year starting on Sunday of the Gregorian calendar. [7]

Nevertheless, some theoretical physics models predict the existence of these magnetic monopoles. Theoretical physics employs Mathematical models and Abstractions of Physics in an attempt to explain experimental data taken of the natural world In Physics, a magnetic monopole is a hypothetical particle that is a Magnet with only one pole (see Maxwell's equations for more on magnetic Paul Dirac observed in 1931 that, because electricity and magnetism show a certain symmetry, just as quantum theory predicts that individual positive or negative electric charges can be observed without the opposing charge, isolated South or North magnetic poles should be observable. Symmetry generally conveys two primary meanings The first is an imprecise sense of harmonious or aesthetically-pleasing proportionality and balance such that it reflects beauty or Quantum electrodynamics ( QED) is a relativistic Quantum field theory of Electrodynamics. A negative number is a Number that is less than zero, such as −2 Using quantum theory Dirac showed that if magnetic monopoles exist, then one could explain the quantization of electric charge---that is, why the observed elementary particles carry charges that are multiples of the charge of the electron. In Particle physics, an elementary particle or fundamental particle is a particle not known to have substructure that is it is not known to be made

Certain grand unified theories predict the existence of monopoles which, unlike elementary particles, are solitons (localized energy packets). Grand Unification, grand unified theory, or GUT refers to any of several very similar unified field theories or models in Physics that In Mathematics and Physics, a soliton is a self-reinforcing solitary wave (a wave packet or pulse that maintains its shape while it travels at constant speed In Physics and other Sciences energy (from the Greek grc ἐνέργεια - Energeia, "activity operation" from grc ἐνεργός The initial results of using these models to estimate the number of monopoles created in the big bang contradicted cosmological observations — the monopoles would have been so plentiful and massive that they would have long since halted the expansion of the universe. The Big Bang is the cosmological model of the Universe that is best supported by all lines of scientific evidence and Observation. However, the idea of inflation (for which this problem served as a partial motivation) was successful in solving this problem, creating models in which monopoles existed but were rare enough to be consistent with current observations. In Physical cosmology, cosmic inflation is the idea that the nascent Universe passed through a phase of exponential expansion that [8]

Units of electromagnetism

SI units related to magnetism

edit
SI electromagnetism units
Symbol Name of Quantity Derived Units Unit Base Units
I Electric current ampere (SI base unit) A A (= W/V = C/s)
q Electric charge, Quantity of electricity coulomb C A·s
V Potential difference or Electromotive force volt V J/C = kg·m2·s−3·A−1
R, Z, X Resistance, Impedance, Reactance ohm Ω V/A = kg·m2·s−3·A−2
ρ Resistivity ohm metre Ω·m kg·m3·s−3·A−2
P Power, Electrical watt W V·A = kg·m2·s−3
C Capacitance farad F C/V = kg−1·m−2·A2·s4
Elastance reciprocal farad F−1 V/C = kg·m2·A−2·s−4
E Electric field volt per metre V/m N/C = kg·m·A−1·s−3
D Electric displacement field coulomb per square metre C/m2 A·s·m−2
ε Permittivity farad per metre F/m kg−1·m−3·A2·s4
χe Electric susceptibility (dimensionless) - -
G, Y, B Conductance, Admittance, Susceptance siemens S Ω−1 = kg−1·m−2·s3·A2
σ Conductivity siemens per metre S/m kg−1·m−3·s3·A2
B Magnetic field (Magnetic flux density) tesla T Wb/m2 = kg·s−2·A−1 = N·A−1·m−1
Φm Magnetic flux weber Wb V·s = kg·m2·s−2·A−1
H Magnetizing field ampere per metre A/m A·m−1
Reluctance ampere-turn per weber A/Wb kg−1·m−2·s2·A2
L Inductance henry H Wb/A = V·s/A = kg·m2·s−2·A−2
μ Permeability henry per metre H/m kg·m·s−2·A−2
χm Magnetic susceptibility (dimensionless) - -

Other units

See also

References

  1. ^ Fowler, Michael (1997). Historical Beginnings of Theories of Electricity and Magnetism. Retrieved on 2008-04-02. 2008 ( MMVIII) is the current year in accordance with the Gregorian calendar, a Leap year that started on Tuesday of the Common Events 68 - Galba, Governor of Hispania, names himself legatus senatus populique Romani, breaking the line of
  2. ^ Li Shu-hua, “Origine de la Boussole 11. Aimant et Boussole,” Isis, Vol. 45, No. 2. (Jul. , 1954), p. 175
  3. ^ Li Shu-hua, “Origine de la Boussole 11. Aimant et Boussole,” Isis, Vol. 45, No. 2. (Jul. , 1954), p. 176
  4. ^ A. Einstein: "On the Electrodynamics of Moving Bodies", June 30, 1905. http://www.fourmilab.ch/etexts/einstein/specrel/www/.
  5. ^ A. Einstein: "On the Electrodynamics of Moving Bodies", June 30, 1905. http://www.fourmilab.ch/etexts/einstein/specrel/www/.
  6. ^ Griffiths, David J. David J Griffiths (born 1942 is a US physicist and educator He has worked at Reed College since 1978 where he is currently the Howard Vollum (1998). Introduction to Electrodynamics, 3rd ed. , Prentice Hall. ISBN 0-13-805326-X.  , chapter 12
  7. ^ Milton mentions some inconclusive events (p. 60) and still concludes that "no evidence at all of magnetic monopoles has survived" (p. 3). Milton, Kimball A. (June 2006). "Theoretical and experimental status of magnetic monopoles". Reports on Progress in Physics 69 (6): 1637–1711. doi:10.1088/0034-4885/69/6/R02. A digital object identifier ( DOI) is a permanent identifier given to an Electronic document.  .
  8. ^ Guth, Alan (1997). Alan Harvey Guth (born February 27, 1947) is a Theoretical physicist and Cosmologist. The Inflationary Universe: The Quest for a New Theory of Cosmic Origins. Perseus. ISBN 0-201-32840-2.  .

External links

Dictionary

magnetism

-noun

  1. The property of being magnetic
  2. The science which treats of magnetic phenomena.
  3. Power of attraction; power to excite the feelings and to gain the affections.
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