# Magnetic field

magnetic fieldsmagneticmagnetic flux densitymagnetic field linesmagnetic field strengthmagnetic field linemagnetizing fieldmagnetic field intensitymagnetic inductionmagnetic-field
A magnetic field is a vector field that describes the magnetic influence of electric charges in relative motion and magnetized materials.wikipedia
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### Vector field

A magnetic field is a vector field that describes the magnetic influence of electric charges in relative motion and magnetized materials.
Vector fields are often used to model, for example, the speed and direction of a moving fluid throughout space, or the strength and direction of some force, such as the magnetic or gravitational force, as it changes from one point to another point.

### Electromagnet

electromagnetselectro-magnetelectromagnetic
Magnetic fields surround and are created by magnetized material and by moving electric charges (electric currents) such as those used in electromagnets.
An electromagnet is a type of magnet in which the magnetic field is produced by an electric current.

### Tesla (unit)

teslaTteslas
, magnetic flux density, is measured in tesla (in SI base units: kilogram per second 2 per ampere), which is equivalent to newton per meter per ampere. (magnetic flux) is measured in webers (symbol: Wb) so that a flux density of 1 Wb/m 2 is 1 tesla.
The tesla (symbol: T) is a derived unit of the magnetic induction (also, magnetic flux density) in the International System of Units.

### Iron

FeFe 2+ Fe(III)
The effects of magnetic fields are commonly seen in permanent magnets, which pull on magnetic materials (such as iron) and attract or repel other magnets.
Below its Curie point of 770 °C, α-iron changes from paramagnetic to ferromagnetic: the spins of the two unpaired electrons in each atom generally align with the spins of its neighbors, creating an overall magnetic field.

### Electric charge

chargeelectrical chargecharged
Magnetic fields surround and are created by magnetized material and by moving electric charges (electric currents) such as those used in electromagnets. Magnetic fields are produced by moving electric charges and the intrinsic magnetic moments of elementary particles associated with a fundamental quantum property, their spin.
An electric charge has an electric field, and if the charge is moving it also generates a magnetic field.

### Electric motor

motorelectric motorsmotors
Rotating magnetic fields are used in both electric motors and generators.
Most electric motors operate through the interaction between the motor's magnetic field and electric current in a wire winding to generate force in the form of rotation of a shaft.

### Earth's magnetic field

geomagnetismgeomagneticgeomagnetic field
The Earth produces its own magnetic field, which shields the Earth's ozone layer from the solar wind and is important in navigation using a compass.
Earth's magnetic field, also known as the geomagnetic field, is the magnetic field that extends from the Earth's interior out into space, where it interacts with the solar wind, a stream of charged particles emanating from the Sun.

### Hall effect

Hall coefficientHall-effectCorbino effect
Magnetic forces give information about the charge carriers in a material through the Hall effect. Important classes of magnetometers include using induction magnetometer (or search-coil magnetometer) which measure only varying magnetic fields, rotating coil magnetometer, Hall effect magnetometers, NMR magnetometers, SQUID magnetometers, and fluxgate magnetometers.
The Hall effect is the production of a voltage difference (the Hall voltage) across an electrical conductor, transverse to an electric current in the conductor and to an applied magnetic field perpendicular to the current.

### Magnetic circuit

Hopkinson's lawMagnetic Circuitsair gap
The interaction of magnetic fields in electric devices such as transformers is studied in the discipline of magnetic circuits.
Magnetic circuits are employed to efficiently channel magnetic fields in many devices such as electric motors, generators, transformers, relays, lifting electromagnets, SQUIDs, galvanometers, and magnetic recording heads.

### Fundamental interaction

fundamental forcesfundamental forcefundamental interactions
Magnetic fields and electric fields are interrelated, and are both components of the electromagnetic force, one of the four fundamental forces of nature.
The electromagnetic force, carried by the photon, creates electric and magnetic fields, which are responsible for the attraction between orbital electrons and atomic nuclei which holds atoms together, as well as chemical bonding and electromagnetic waves, including visible light, and forms the basis for electrical technology.

### Hans Christian Ørsted

ØrstedHans Christian OerstedH.C. Ørsted
Hans Christian Ørsted demonstrated that a current-carrying wire is surrounded by a circular magnetic field.
Hans Christian Ørsted (, ; often rendered Oersted in English; 14 August 1777 – 9 March 1851) was a Danish physicist and chemist who discovered that electric currents create magnetic fields, which was the first connection found between electricity and magnetism.

### Electric field

electricelectrostatic fieldelectrical field
Magnetic fields and electric fields are interrelated, and are both components of the electromagnetic force, one of the four fundamental forces of nature.
Electric fields are created by electric charges, or by time-varying magnetic fields.

He described this phenomenon in what is known as Faraday's law of induction.
Faraday's law of induction (briefly, Faraday's law) is a basic law of electromagnetism predicting how a magnetic field will interact with an electric circuit to produce an electromotive force (EMF)—a phenomenon called electromagnetic induction.

### Biot–Savart law

Biot-Savart lawBiot-Savart-FormulaBiot–Savart equation
Laplace later deduced, but did not publish, a law of force based on the differential action of a differential section of the wire, which became known as the Biot–Savart law.
In physics, specifically electromagnetism, the Biot–Savart law ( or ) is an equation describing the magnetic field generated by a constant electric current.

### Electromagnetism

electromagneticelectrodynamicselectromagnetic force
Magnetic fields and electric fields are interrelated, and are both components of the electromagnetic force, one of the four fundamental forces of nature. In electromagnetics, the term "magnetic field" is used for two distinct but closely related fields denoted by the symbols
The electromagnetic force is carried by electromagnetic fields composed of electric fields and magnetic fields, and it is responsible for electromagnetic radiation such as light.

### Maxwell's equations

Maxwell equationsMaxwell equationMaxwell’s equations
Between 1861 and 1865, James Clerk Maxwell developed and published Maxwell's equations, which explained and united all of classical electricity and magnetism.
The equations provide a mathematical model for electric, optical, and radio technologies, such as power generation, electric motors, wireless communication, lenses, radar etc. Maxwell's equations describe how electric and magnetic fields are generated by charges, currents, and changes of the fields.

### James Clerk Maxwell

MaxwellJ. C. MaxwellJames Maxwell
Between 1861 and 1865, James Clerk Maxwell developed and published Maxwell's equations, which explained and united all of classical electricity and magnetism.
With the publication of "A Dynamical Theory of the Electromagnetic Field" in 1865, Maxwell demonstrated that electric and magnetic fields travel through space as waves moving at the speed of light.

### Compass

magnetic compassDigital compassmariner's compass
The Earth produces its own magnetic field, which shields the Earth's ozone layer from the solar wind and is important in navigation using a compass.
The magnetic field exerts a torque on the needle, pulling the North end or pole of the needle approximately toward the Earth's North magnetic pole, and pulling the other toward the Earth's South magnetic pole.

### Lorentz force

magnetic forceLorentz force lawLorentz
The velocity dependent portion can be separated such that the force on the particle satisfies the Lorentz force law,
A particle of charge q moving with a velocity v in an electric field E and a magnetic field B experiences a force of

### Spin (physics)

spinnuclear spinspins
Magnetic fields are produced by moving electric charges and the intrinsic magnetic moments of elementary particles associated with a fundamental quantum property, their spin.
These magnetic moments can be experimentally observed in several ways, e.g. by the deflection of particles by inhomogeneous magnetic fields in a Stern–Gerlach experiment, or by measuring the magnetic fields generated by the particles themselves.

### Vacuum

free spaceevacuatedhigh vacuum
In a vacuum,
:relating the electric displacement field D to the electric field E and the magnetic field or H-field H to the magnetic induction or B-field B.

### Magnetometer

digital compassDigitalmagnetometry
Magnetometers are devices used to measure the local magnetic field. Important classes of magnetometers include using induction magnetometer (or search-coil magnetometer) which measure only varying magnetic fields, rotating coil magnetometer, Hall effect magnetometers, NMR magnetometers, SQUID magnetometers, and fluxgate magnetometers.
A magnetometer is a device that measures magnetism—the direction, strength, or relative change of a magnetic field at a particular location.

### Oersted

megagauss oerstedsOeOERSTEDS
-field is measured in amperes per metre (A/m) in SI units, and in oersteds (Oe) in cgs units.
The oersted (symbol Oe) is the unit of the auxiliary magnetic field H in the centimetre–gram–second system of units (CGS).  It is equivalent to 1 dyne per maxwell.

### Magnetic flux

fluxfluxes definition of flux used in electromagnetism
(magnetic flux) is measured in webers (symbol: Wb) so that a flux density of 1 Wb/m 2 is 1 tesla.
) through a surface is the surface integral of the normal component of the magnetic field flux density B passing through that surface.

### SQUID

superconducting quantum interference devicesuperconducting quantum interference devicesDC SQUID
Important classes of magnetometers include using induction magnetometer (or search-coil magnetometer) which measure only varying magnetic fields, rotating coil magnetometer, Hall effect magnetometers, NMR magnetometers, SQUID magnetometers, and fluxgate magnetometers.
A SQUID (for superconducting quantum interference device) is a very sensitive magnetometer used to measure extremely subtle magnetic fields, based on superconducting loops containing Josephson junctions.