 Current flowing through a wire produces a magnetic field ( B, labeled M here) around the wire. The field is oriented according to the right-hand rule. - For other senses of this term, see magnetic field (disambiguation).
In physics, a magnetic field is the relativistic part of an electric field (as explained by Einstein in 1905). When an electric charge is moving from the perspective of an observer, the electric field of this charge due to space contraction is no longer seen by the observer as spherically symmetric (and due to time dilation not radial) and must be computed using the Lorentz transformations. One of the products of these transformations is the part of electric field which only acts on moving charges - and we call it "magnetic field". Illustration of a magnetic field around a wire through which current is flowing. ...
Illustration of a magnetic field around a wire through which current is flowing. ...
In mathematics and physics, the right-hand rule is a convention for determining relative directions of certain vectors. ...
Magnetic field can refer to: A magnetic field, the physical phenomenon produced by moving electric charges and exhibited by ferrous materials. ...
Physics is the science of Nature. ...
In physics, an electric field or E-field is an effect produced by an electric charge (or a time-varying magnetic field) that exerts a force on charged objects in the field. ...
Electric charge is a fundamental conserved property of some subatomic particles, which determines their electromagnetic interactions. ...
Relativistic effect of apparent contraction of coordinates of moving reference frame in the direction of motion when seen from non moving refernce frame. ...
Time dilation is the phenomenon where the observed time rate of an observers reference frame is different from that of a different reference frame. ...
The Lorentz transformation (LT), named after its discoverer, the Dutch physicist and mathematician Hendrik Antoon Lorentz (1853-1928), forms the basis for the special theory of relativity, which has been introduced to remove contradictions between the theories of electromagnetism and classical mechanics. ...
The quantum-mechanical motion of electrons in atoms produces magnetic fields of permanent ferromagnets. Spinning charged particles also have magnetic moment. Some electrically neutral particles (like neutron) with non-zero spin also have magnetic moment due to charge distribution in their inner structure. Spin-zero particles never have magnetic moment. For a non-technical introduction to the topic, please see Introduction to Quantum mechanics. ...
Ferromagnetism is a phenomenon by which a material can exhibit a spontaneous magnetization, and is one of the strongest forms of magnetism. ...
The terms spin and SPIN have several meanings, including those primarily discussed as spinning: For spin in sub-atomic physics, see spin (physics) For the stalled aircraft maneuver or any of several forms of loss of control in aircraft, see spin (flight) For the periodical, see Spin Magazine For the...
In physics, the magnetic moment or magnetic dipole moment is a measure of the strength of a magnetic source. ...
Properties In physics, the neutron is a subatomic particle with no net electric charge and a mass of 939. ...
A magnetic field is a vector field: it associates with every point in space a (pseudo-)vector that may vary in time. The direction of the field is the equilibrium direction of a magnetic dipole (like a compass needle) placed in the field. Vector field given by vectors of the form (-y, x) In mathematics a vector field is a construction in vector calculus which associates a vector to every point in a Euclidean space. ...
In physics and mathematics, a pseudovector (or axial vector) is a quantity that transforms like a vector under a proper rotation, but gains an additional sign flip under an improper rotation (a transformation that can be expressed as an inversion followed by a proper rotation). ...
In physics and in vector calculus, a spatial vector is a concept characterized by a magnitude, which is a scalar, and a direction (which can be defined in a 3-dimensional space by the Euler angles). ...
The Earths magnetic field, which is approximately a dipole. ...
Compass in a wooden box A compass (or mariners compass) is a navigational instrument for finding directions on the earth. ...
Definition Lorentz transformation of spherically symmetric proper electric field E of moving electric charge (for example, electric field of an electron moving in a conducting wire) from charge's reference frame to non-moving observer's reference frame results in the following term: The word proper may refer to the following things: The proper is that part of a Christian liturgy that is specific to the date within the Liturgical Year. ...
In physics, an electric field or E-field is an effect produced by an electric charge (or a time-varying magnetic field) that exerts a force on charged objects in the field. ...
Electric charge is a fundamental conserved property of some subatomic particles, which determines their electromagnetic interactions. ...
Properties The electron is a lightweight fundamental subatomic particle that carries a negative electric charge. ...
 which we label as "magnetic field" and use the symbol B for it for the sake of mathematical simplicity (one symbol instead of seven).
As seen from the definition, the unit of magnetic field is newton-second per coulomb-meter (or newton per ampere-meter) and is called the tesla. The tesla (symbol T) is the SI derived unit of magnetic flux density (or magnetic induction). ...
Like the electric field, the magnetic field exerts force on electric charge—but only on moving charge: In physics, an electric field or E-field is an effect produced by an electric charge (or a time-varying magnetic field) that exerts a force on charged objects in the field. ...
In physics, a net force acting on a body causes that body to accelerate; that is, to change its velocity. ...
 where - F is the force produced, measured in newtons
 indicates a vector cross product  is electric charge that the magnetic field is acting on, measured in coulombs  is velocity of the electric charge , measured in metres per second Because magnetic field is the relativistic product of Lorentz transformations, the force it produces is called the Lorentz force. The newton (symbol: N) is the SI unit of force. ...
In mathematics, the cross product is a binary operation on vectors in a three-dimensional Euclidean space. ...
Electric charge is a fundamental conserved property of some subatomic particles, which determines their electromagnetic interactions. ...
The coulomb (symbol: C) is the SI unit of electric charge. ...
The velocity of an object is simply its speed in a particular direction. ...
Electric charge is a fundamental conserved property of some subatomic particles, which determines their electromagnetic interactions. ...
Metre per second (U.S. spelling: meter per second) is an SI derived unit of both speed (scalar) and velocity (vector), defined by distance in metres divided by time in seconds. ...
A Lorentz transformation (LT) is a linear transformation that preserves the spacetime interval between any two events in Minkowski space, while leaving the origin fixed (=rotation of Minkowski space). ...
In physics, the Lorentz force is the force exerted on a charged particle in an electromagnetic field. ...
The force due to the magnetic field is different in different frames—moving magnetic field transforms partially or fully back into electric fields under Lorentz transformations. This results in Faraday induction law. A Lorentz transformation (LT) is a linear transformation that preserves the spacetime interval between any two events in Minkowski space, while leaving the origin fixed (=rotation of Minkowski space). ...
Magnetic field of flow (current) of charged particles Substituting into the definition of magnetic field  the proper electric field of point-like charge (see Coulomb's law) In physics, an electric field or E-field is an effect produced by an electric charge (or a time-varying magnetic field) that exerts a force on charged objects in the field. ...
In physics, Coulombs law is an inverse-square law indicating the magnitude and direction of electrostatic force that one stationary, electrically charged object of small dimensions (ideally, a point source) exerts on another. ...
 results in the equation of magnetic field of moving charge:  which is usually called Biot-Savart law. The Biot-Savart law is a physical law with applications in both electromagnetics and aerodynamics. ...
Here
- q is electric charge—motion of which creates the magnetic field—measured in coulombs
- v is velocity of the electric charge q that is generating B, measured in metres per second
- B is the magnetic field (measured in teslas)
Electric charge is a fundamental conserved property of some subatomic particles, which determines their electromagnetic interactions. ...
The velocity of an object is simply its speed in a particular direction. ...
Electric charge is a fundamental conserved property of some subatomic particles, which determines their electromagnetic interactions. ...
Metre per second (U.S. spelling: meter per second) is an SI derived unit of both speed (scalar) and velocity (vector), defined by distance in metres divided by time in seconds. ...
The tesla (symbol T) is the SI derived unit of magnetic flux density (or magnetic induction). ...
Lorentz force on wire segment Integrating Lorentz force on individual charged particle over flow (current) of charged particles results in the Lorentz force on a stationary wire carrying electric current: - F = iBl
where - F = force (newton)
- B = magnetic field (tesla)
- l = length of wire (meter)
- i = current in wire (ampere)
In the equation above, the current vector i is a vector with magnitude equal to the scalar current, i, and direction pointing along the wire that the current is flowing.
Alternatively, instead of current the wire segment l can be considered a vector.
Vector calculus Separating electric field of moving charge into stationary electric and stationary magnetic components (= as measured by stationary observer)—which are usually labeled as E and B—replaces complex Einstein relativistic field transformation equations by more compact and elegant mathematical statements known as Maxwell equations. Two of them which describe magnetic component are: Maxwells equations are the set of four equations, attributed to James Clerk Maxwell, that describe the behavior of both the electric and magnetic fields, as well as their interactions with matter. ...
  where  is the curl operator  is the divergence operator  is permeability  is current density  is the partial derivative  is the free-space permittivity  is the electric field  is time The first equation is known as Ampère's law with James Clerk Maxwell's correction. The second term of this equation (Maxwell's correction) disappears in static (time independent) systems. The second equation is a statement of the observed non-existence of magnetic monopoles. These are two of four Maxwell's equations written in differential notation (introduced by Oliver Heaviside). This article is about the cURL command line tool. ...
In vector calculus, the divergence is an operator that measures a vector fields tendency to originate from or converge upon a given point. ...
In electromagnetism, permeability is the degree of magnetisation of a material that responds linearly to an applied magnetic field. ...
In electricity, current is the rate of flow of charges, usually through a metal wire or some other electrical conductor. ...
In mathematics, a partial derivative of a function of several variables is its derivative with respect to one of those variables with the others held constant (as opposed to the total derivative, in which all variables are allowed to vary). ...
Permittivity is a physical quantity that describes how an electric field affects and is affected by a dielectric medium and is determined by the ability of a material to polarize in response to an applied electric field, and thereby to cancel, partially, the field inside the material. ...
In physics, an electric field or E-field is an effect produced by an electric charge (or a time-varying magnetic field) that exerts a force on charged objects in the field. ...
A pocket watch. ...
André-Marie Ampère (January 22, 1775 – June 10, 1836), was a French physicist who is generally credited as one of the main discoverers of electromagnetism. ...
James Clerk Maxwell (13 June 1831 – 5 November 1879) was a Scottish mathematical physicist, born in Edinburgh. ...
In physics, a magnetic monopole is a hypothetical particle that may be loosely described as a magnet with only one pole (see electromagnetic theory for more on magnetic poles). ...
Maxwells equations (sometimes called the Maxwell equations) are the set of four equations, attributed to James Clerk Maxwell, that describe the behavior of both the electric and magnetic fields, as well as their interactions with matter. ...
Oliver Heaviside (May 18, 1850 – February 3, 1925) was a self-taught English engineer, mathematician and physicist who adapted complex numbers to the study of electrical circuits, developed techniques for applying Laplace transforms to the solution of differential equations, reformulated Maxwells field equations in terms of electric and magnetic...
Energy in the magnetic field If we divide the energy of a long (or toroidal) solenoid LI2 / 2 by the volume of the solenoid, the density of magnetic field energy can be obtained:  For example, magnetic field B = 1 tesla has energy density about 398 kilojoules per cubic meter, and of 10 teslas, about 40 megajoules per cubic meter.
The same is the pressure produced by magnetic field (pressure and energy density are essentially the same physical quantities and thus have the same units). Thus, magnetic field of 1 tesla produces pressure of 398 kPa (about 4 atmospheres), and 10 T about 40 Mpa (~400 atm).
Symbols and terminology Magnetic field is usually denoted by the symbol  . Historically, was called the magnetic flux density or magnetic induction. A distinct quantity,  , was called the magnetic field, and this terminology is still often used to distinguish the two in the context of magnetic materials (non-trivial permeability μ). Otherwise, however, this distinction is often ignored, and both quantities are frequently referred to as "the magnetic field." (Some authors call H the auxiliary field, instead.) In linear materials, such as air or free space, the two quantities are linearly related: Magnetic field density, otherwise known as magnetic flux density, is essentially what the layman knows as a magnetic field - akin to a gravitational or electric field. ...
In electromagnetism, permeability is the degree of magnetisation of a material that responds linearly to an applied magnetic field. ...
 where  is the magnetic permeability (in henries per meter) of the medium. In electromagnetism, permeability is the degree of magnetisation of a material that responds linearly to an applied magnetic field. ...
The henry (symbol H) is the SI unit of inductance. ...
The metre, or meter (symbol: m) is the SI base unit of length. ...
In SI units, and  are measured in teslas (T) and amperes per meter (A/m), respectively; or, in cgs units, in gauss (G) and oersteds (Oe), respectively. Two parallel wires carrying an electric current in the same sense will generate a magnetic field which will cause a force of attraction to each other. This fact is used to generate the value of an ampere of electric current. Note that while like charges repel and unlike ones attract, the opposite holds for currents: if the current in one of the two parallel wires is reversed, the two will repel. Cover of brochure The International System of Units. ...
The tesla (symbol T) is the SI derived unit of magnetic flux density (or magnetic induction). ...
The ampere (symbol: A) is the SI base unit of electric current equal to one coulomb per second. ...
The metre, or meter (symbol: m) is the SI base unit of length. ...
CGS is an acronym for centimetre-gram-second. ...
The gauss, abbreviated as G, is the cgs unit of magnetic flux density or magnetic induction (B), named after the German mathematician and physicist Carl Friedrich Gauss. ...
The oersted is old CGS unit of magnetic field strength (or magnetic induction). ...
The ampere (symbol: A) is the SI base unit of electric current equal to one coulomb per second. ...
Properties Maxwell did much to unify static electricity and magnetism, producing a set of four equations relating the two fields. However, under Maxwell's formulation, there were still two distinct fields describing different phenomena. It was Albert Einstein who showed, using special relativity, that electric and magnetic fields are two aspects of the same thing (a rank-2 tensor), and that one observer may perceive a magnetic force where a moving observer perceives only an electrostatic force. Thus, using special relativity, magnetic forces are a manifestation of electrostatic forces of charges in motion and may be predicted from knowledge of the electrostatic forces and the velocity of movement (relative to some observer) of the charges. Albert Einstein, photographed by Yousuf Karsh in 1948. ...
For a non-technical introduction to the topic, please see Introduction to Special relativity. ...
In mathematics, a tensor is (in an informal sense) a generalized linear quantity or geometrical entity that can be expressed as a multi-dimensional array relative to a choice of basis; however, as an object in and of itself, a tensor is independent of any chosen frame of reference. ...
Electrostatics is the branch of physics that deals with the force exerted by a static (i. ...
Changing magnetic field is mathematically the same as moving magnetic field (see relativity of motion)— thus according to Einstein's field transformation equations (= Lorentz transformation of field from proper reference frame to non-moving reference frame) part of it appears as electric field component— this is known as Faraday's law of induction and is the principle behind electric generators and electric motors. In physics, the term relativity is used in several, related contexts: Galileo first developed the principle of relativity, which is the postulate that the laws of physics are the same for all observers. ...
The word proper may refer to the following things: The proper is that part of a Christian liturgy that is specific to the date within the Liturgical Year. ...
Faradays law of induction gives the relation between the rate of change of the magnetic flux through the surface S enclosed by a contour C and the electric field induced along the contour: where E is the induced electric field, dl is an infinitesimal element of the contour C...
Generator redirects here. ...
Rotating magnetic field as a sum of magnetic vectors from 3 phase coils. ...
Magnetic field lines
 Magnetic field lines shown by iron filings The direction of the magnetic field vector follows from the definition (see above). It coincides with the direction of orientation of magnetic dipole— - like a small magnet or a small loop of current in the magnetic field, or a bunch of small particles of ferromagnetic material (see figure). Magnet from Practical Physics, publ. ...
Magnet from Practical Physics, publ. ...
This article is about the electromagnetic phenomenon. ...
Ferromagnetism is a phenomenon by which a material can exhibit a spontaneous magnetization, and is one of the strongest forms of magnetism. ...
Pole labelling confusions Because the end of compass needle pointing north was historically called the north magnetic pole of the needle, and because dipoles (being vectors) align "head to tail" versus each other, the north pole of a compass needle actually points toward Earth's south magnetic pole (which is located in northern Canada). Compass in a wooden box A compass (or mariners compass) is a navigational instrument for finding directions on the earth. ...
The Earths magnetic field, which is approximately a dipole. ...
The word vector means carrier in Latin; it is derived from the Latin verb vehere, which means to carry. ...
The "north" and "south" poles of a magnet or a magnetic dipole are labelled similar to north and south poles of a compass needle. Near the north pole of a bar or a cylinder magnet, the magnetic field vector is directed out of the magnet; near the south pole, into the magnet. This magnetic field continues inside of magnet (so there are no actual "poles" anywhere inside or outside of a magnet). Breaking a magnet in half does not separate the poles but produces two magnets with two "poles" each. This article is about the electromagnetic phenomenon. ...
Earth's magnetic field is produced by electric currents in its liquid core. Electric current is the flow of electric charge. ...
Field density Magnetic field density, otherwise known as magnetic flux density, is essentially what the layman knows as a magnetic field —akin to a gravitational or electric field. It is a response of a medium to the presence of a magnetic field. The SI unit of magnetic flux density is the tesla. 1 tesla = 1 weber per square metre. The gravitational field is a field that causes bodies with mass to attract each other. ...
In physics, an electric field or E-field is an effect produced by an electric charge (or a time-varying magnetic field) that exerts a force on charged objects in the field. ...
Cover of brochure The International System of Units. ...
The tesla (symbol T) is the SI derived unit of magnetic flux density (or magnetic induction). ...
In physics, the weber (symbol: Wb) is the SI unit of magnetic flux. ...
A square metre (US spelling: square meter) is by definition the area enclosed by a square with sides each 1 metre long. ...
It can be more easily explained if one works backwards from the equation: 
where
- B is the magnitude of flux density in teslas
- F is the force in newtons experienced by a wire carrying
- I amperes of current
- L metres in length
 Demonstration of the left hand rule So, one can see for a magnetic flux density to equal 1 tesla, a force of 1 newton must act on a wire of length 1 metre carrying 1 ampere of current. 1 newton is a lot of force, and is not easily accomplished. To put it in perspective: the most powerful superconducting electromagnets in the world have flux densities of 'only' 20 T. This is true obviously for both electromagnets and natural magnets, but a magnetic field can only act on moving charge—hence the current, I, in the equation. Indeed, the equation can be adjusted to incorporate moving single charges, ie protons, electrons, and so on via In the various subfields of physics, there exist two common usages of the term flux, both with rigorous mathematical frameworks. ...
The tesla (symbol T) is the SI derived unit of magnetic flux density (or magnetic induction). ...
In physics, a force is defined as the rate of change of momentum of that body. ...
The newton (symbol: N) is the SI unit of force. ...
The ampere (symbol: A) is the SI base unit of electric current equal to one coulomb per second. ...
In electricity, current is the rate of flow of charges, usually through a metal wire or some other electrical conductor. ...
The metre, or meter, is a measure of length, approximately equal to 3. ...
In general English usage, length (symbols: l, L) is one particular instance of distance: an objects length is its extent along its longest dimension. ...
my own creation - the left hand rule File history Legend: (cur) = this is the current file, (del) = delete this old version, (rev) = revert to this old version. ...
my own creation - the left hand rule File history Legend: (cur) = this is the current file, (del) = delete this old version, (rev) = revert to this old version. ...
The newton (symbol: N) is the SI unit of force. ...
The metre, or meter, is a measure of length, approximately equal to 3. ...
The ampere (symbol: A) is the SI base unit of electric current equal to one coulomb per second. ...
A magnet levitating above a high-temperature superconductor (with boiling liquid nitrogen underneath) demonstrates the Meissner effect. ...
An electromagnet is a type of magnet in which the magnetic field is produced by a flow of electric current. ...
where
- Q is 1 coulomb of charge
- v is the velocity of that charge in metre per second
Fleming's left hand rule can be used to determine the direction of motion/current/polarity from any two of those, as seen in the example. It can also remembered in the following way. From the thumb to second finger, indicating 'Force', 'B-field', and 'I(Current)' respectively. Therefore it is F-B-I in short. For professional languages, right hand grip rule is used instead which originated from the definition of cross product in the right hand system of coordinates. The coulomb (symbol: C) is the SI unit of electric charge. ...
Metre per second (U.S. spelling: meter per second) is an SI derived unit of both speed (scalar) and velocity (vector), defined by distance in metres divided by time in seconds. ...
Sir John Ambrose Fleming (, November 29, 1849 - April 18, 1945) was an English electrical engineer and physicist. ...
The right hand rule is a physics priciple applied to electricity passing through a solenoid, resulting in a magnetic field. ...
In mathematics, the cross product is a binary operation on vectors in a three-dimensional Euclidean space. ...
See Cartesian coordinate system or Coordinates (elementary mathematics) for a more elementary introduction to this topic. ...
Other units of magnetic flux density are
- 1 gauss = 10-4 teslas = 100 microteslas (µT)
- 1 gamma = 10-9 teslas = 1 nanotesla (nT)
For a biography of the mathematician, see: Carl Friedrich Gauss The gauss, abbreviated as G, is the cgs unit of magnetic flux density or magnetic induction (B), named after the German mathematician and physicist Carl Friedrich Gauss. ...
Gamma (uppercase Γ, lowercase γ) is the third letter of the Greek alphabet. ...
Rotating magnetic fields A rotating magnetic field is a magnetic field which periodically changes direction. This is a key principle to the operation of alternating-current motor. A permanent magnet in such a field will rotate so as to maintain its alignment with the external field. This effect was utilised in early alternating current electric motors. A rotating magnetic field can be constructed using two orthogonal coils with 90 degrees phase difference in their AC currents. However, in practice such a system would be supplied through a three-wire arrangement with unequal currents. This inequality would cause serious problems in standardization of the conductor size and in order to overcome it, three-phase systems are used where the three currents are equal in magnitude and have 120 degrees phase difference. Three similar coils having mutual geometrical angles of 120 degrees will create the rotating magnetic field in this case.The ability of the three phase system to create a rotating field utilized in electric motors is one of the main reasons why three phase systems dominated in the world electric power supply systems. Because magnets degrade with time, synchronous motors and induction motors use short-circuited rotors (instead of a magnet) following rotating magnetic field of multicoiled stator. (Short circuited turns of rotor develop eddy currents in rotating field of stator which (currents) in turn move the rotor by Lorentz force). An alternator is an electromechanical device that converts mechanical energy to alternating current electrical energy. ...
Rotating magnetic field as a sum of magnetic vectors from 3 phase coils. ...
shading-coils within the magnetic circuit of the field coil Shaded-pole synchronous motors are a class of AC motor. ...
Electric motors of various sizes. ...
R0t0r is from efnet ...
The stator is the fixed part of a rotating machine. ...
As the circular plate moves down through a small region of constant magnetic field directed into the page, eddy currents are induced in the plate. ...
In 1882, Nikola Tesla identified the concept of the rotating magnetic field. In 1885, Galileo Ferraris independently researched the concept. In 1888, Tesla gained U.S. Patent 381968 for his work. Also in 1888, Ferraris published his research in a paper to the Royal Academy of Sciences in Turin. 1882 (MDCCCLXXXII) was a common year starting on Sunday (see link for calendar). ...
This article or section is in need of attention from an expert on the subject. ...
1885 (MDCCCLXXXV) is a common year starting on Thursday. ...
Galileo Ferraris (October 30, 1847 - February 7, 1897) was an Italian physicist and electrical engineer, noted mostly for his studies on alternating current. ...
1888 (MDCCCLXXXVIII) is a leap year starting on Sunday (click on link for calendar) of the Gregorian calendar or a leap year starting on Tuesday of the Julian calendar. ...
Turin (Italian: ; Piedmontese: TürÃn) is a major industrial city in north-western Italy, capital of the Piedmont region, located mainly on the west bank of the Po River. ...
Hall effect - Main article: hall effect
Because Lorentz force is charge sign dependent (see above), it results in a charges separation, when a conductor with current is placed in transverse magnetic field—with a buildup of opposite charges on two opposite sides of conductor (in the direction normal to the magnetic field direction)—and the potential difference between these sides can be measured. Hall effect diagram, showing electron flow (rather than conventional current). ...
In physics, the Lorentz force is the force exerted on a charged particle in an electromagnetic field. ...
Hall effect is often used to measure the magnitude of a magnetic field as well as to find the sign of dominant charge carriers in semiconductors (negative electrons or positive holes). Hall effect diagram, showing electron flow (rather than conventional current). ...
Magnetic field of celestial bodies A rotating body of conductive gas or liquid develops self amplifying electric currents (thus self generates magnetic field) due to combination of differential rotation (different angular velocity of different parts of body), Coriolis force and induction. Distribution of currents can be quite complicated, with numerous open and closed loops - thus the magnetic field of these currents in their immediate vicinity is also quite multitwisted. At large distance, however, magnetic field of currents flowing in opposite direction cancels out and only a major dipole field survives (diminishes with distance most slow). Because major currents flow in the direction of conductive mass motion (equatorial currents) then the major component of generated magnetic field is the dipole field of equatorial current loop, thus producing magnetic poles near geographic poles of a rotating body. In electricity, current refers to electric current, which is the flow of electric charge. ...
In physics, the Coriolis effect is an inertial force first described by Gaspard-Gustave Coriolis, a French scientist, in 1835. ...
Magnetic fields of all celestial bodies are more or less aligned with the direction of rotation. Another feature of this dynamo model is that the currents are AC rather than DC - their direction (thus the direction of the magnetic field they generate) periodically (more or less) alternates, changing amplitude and reversing direction (which is still more or less aligned with the axis of rotation).
The sun's major component of magnetic field reverses direction every 11 years (so the period is about 22 years), resulting in diminished magnitude of magnetic field near reversal time. During this dormancy time the sunspots activity is maximized (because of lack of magnetic braking on plasma) and as a result - massive ejection of high energy plasma into solar corona and interplanetary space takes place. Collision of neighboring sunspots with oppositely directed magnetic field results in generation of strong electric field near rapidly disappearing magnetic field regions. This electric field accelerates electrons and protons to high energies (kiloelectron volts) which results in jets of extremely hot plasma leaving Sun's surface and heating coronal plasma to high temperatures (millions K). A sunspot is a region on the Suns surface (photosphere) that is marked by a lower temperature than its surroundings and intense magnetic activity, which inhibits convection, forming areas of low surface temperature. ...
The corona is the luminous plasma atmosphere of the Sun extending millions of kilometres into space, most easily seen during a total solar eclipse, but also observable in a coronagraph. ...
Compact and fast rotating astronomical objects (white dwarfs, neutron stars and black holes) have extremely strong magnetic fields. The magnetic field of a newly born fast spinning neutron star is so strong (up to 10^8 Teslas) that it electromagnetically radiates enough energy to quickly (in a matter of few million years) damp down the star rotation 100-1000 times. Matter falling onto neutron star also has to follow magnetic field lines, resulting in two hot spots on the surface where it can reach and impact star's surface. These spots are literally few feet across but tremendously bright. Their periodic eclipsing during star rotation is believed to be the source of pulsating radiation (see pulsars). White dwarf Sirius-B in x-rays A white dwarf is an astronomical object which is produced when a low or medium mass star dies. ...
A neutron star is one of the few possible endpoints of stellar evolution. ...
A black hole is a concentration of mass great enough that the force of gravity prevents anything past its event horizon from escaping it except through quantum tunnelling behaviour (known as Hawking Radiation). ...
Composite Optical/X-ray image of the Crab Nebula pulsar, showing surrounding nebular gases stirred by the pulsars magnetic field and radiation. ...
Jets of relativistic plasma are often observed along the direction of magnetic poles of active black holes in centers of young galaxies.
If the gas or liquid is very viscosious (resulting in turbulent differential motion) then the reversal of magnetic field may not be very periodic. This is the case of Earth's magnetic field which is generated by turbulent currents in viscosious outer core. Turbulent flow around an obstacle; the flow further away is laminar Laminar and turbulent water flow over the hull of a submarine Turbulence creating a vortex on an airplane wing In fluid dynamics, turbulence or turbulent flow is a flow regime characterized by low-momentum diffusion, high momentum convection, and...
See also General - Electric field - effect produced by an electric charge that exerts a force on charged objects in its vicinity.
- Electromagnetic field - a field composed of two related vector fields, the electric field and the magnetic field.
- Electromagnetism - the physics of the electromagnetic field: a field, encompassing all of space, composed of the electric field and the magnetic field.
- Magnetism - phenomenon by which materials exert an attractive or repulsive force on other materials.
- Magnetohydrodynamics - the academic discipline which studies the dynamics of electrically conducting fluids.
- SI electromagnetism units
Mathematics In physics, an electric field or E-field is an effect produced by an electric charge (or a time-varying magnetic field) that exerts a force on charged objects in the field. ...
To meet Wikipedias quality standards, this article or section may require cleanup. ...
Electromagnetism is the physics of the electromagnetic field: a field, encompassing all of space, which exerts a force on those particles that possess the property of electric charge, and is in turn affected by the presence and motion of such particles. ...
In physics, magnetism is one of the phenomena by which materials exert an attractive or repulsive force on other materials. ...
Magnetohydrodynamics (MHD) (magnetofluiddynamics or hydromagnetics), is the academic discipline which studies the dynamics of electrically conducting fluids. ...
...
- Ampère's law - magnetic equivalent of Gauss's law.
- Biot-Savart law - describes the magnetic field set up by a steadily flowing line current.
- Magnetic helicity - extent to which a magnetic field "wraps around itself".
- Maxwell's equations - four equations describing the behavior of the electric and magnetic fields, and their interaction with matter.
Applications An electric current produces a magnetic field. ...
The Biot-Savart law is a physical law with applications in both electromagnetics and aerodynamics. ...
this page is about helicity in magnetic fields. ...
Maxwells equations (sometimes called the Maxwell equations) are the set of four equations, attributed to James Clerk Maxwell, that describe the behavior of both the electric and magnetic fields, as well as their interactions with matter. ...
- Helmholtz coil - a device for producing a region of nearly uniform magnetic field.
- Maxwell coil - a device for producing a large volume of almost constant magnetic field.
- Earth's magnetic field - a discussion of the magnetic field of the Earth.
- Dynamo theory - a proposed mechanism for the creation of the Earth's magnetic field.
- Electric motor - AC motors used magnetic fields
The term Helmholtz coils refers to a device for producing a region of nearly uniform magnetic field. ...
Maxwell coil layout in cylindrical coordinates. ...
This article or section does not cite its references or sources. ...
The Dynamo theory proposes a mechanism by which a celestial body such as the Earth generates a magnetic field. ...
Rotating magnetic field as a sum of magnetic vectors from 3 phase coils. ...
References Books - Griffiths, David J. (1998). Introduction to Electrodynamics (3rd ed.). Prentice Hall. ISBN 013805326X.
- Jackson, John D. (1998). Classical Electrodynamics (3rd ed.). Wiley. ISBN 047130932X.
- Tipler, Paul (2004). Physics for Scientists and Engineers: Electricity, Magnetism, Light, and Elementary Modern Physics (5th ed.). W. H. Freeman. ISBN 0716708108.
External articles Information - Field density
- Jiles, David (1994). Introduction to Electronic Properties of Materials (1st ed.). Springer. ISBN 0-412-49580-5.
Rotating magnetic fields July 17 is the 198th day (199th in leap years) of the year in the Gregorian calendar, with 167 days remaining. ...
Template:Diffgggtgerent calendars 2005 (MMV) was a common year starting on Saturday of the Gregorian calendar. ...
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