# Oersted

Oersted

Oersted (abbreviated as Oe) is the unit of magnetizing field (also known as H-field, magnetic field strength or intensity) in the CGS system of units.

## Difference between cgs and SI systems

In cgs the unit of H-field is the oersted and the unit of B-field is the gauss. In the SI system, Ampere per meter (A/m) is used for H-field and Tesla is used for B-field.[1]

## History

The unit was established by the IEC in 1930 [2] in honour of the Danish physicist Hans Christian Ørsted.

## Definition

The oersted is defined as an dyne per unit pole.[citation needed] The Oersted is 1000/4π (≈79.5774715) ampere per meter, in terms of SI units.[3][4][5][6]

So, the H-field strength inside a long solenoid wound with 79.58 turns per meter of a wire carrying 1 A will be approximately 1 oersted. The preceding statement is exactly correct if the solenoid considered is infinite in length and the current evenly distributed over its surface.

The oersted is closely related to the gauss, the CGS unit of magnetic flux density. In a vacuum, if the magnetizing field strength is 1 Oe, then the magnetic field density is 1 Gs, whereas in a medium having permeability μr (relative to permeability of vacuum), their relation is:

B(G) = μr * H(Oe)

Because oersteds are used to measure magnetizing field strength, they are also related to magnetomotive force (mmf) of current in a single-winding wire-loop:

$H(\mbox{Oe})= \frac{1000}{4 \pi} \frac{I(\mbox{A})}{l(\mbox{m})}$

The stored energy in a magnet, called magnet performance or maximum energy product (often abbreviated BHmax), is typically measured in units of megagauss-oersteds (MGOe). One MGOe is approximately equal to 7957.74715 J/m3.[7]

## References

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### Look at other dictionaries:

• oersted — OERSTÉD, oerstezi, s.m. Unitate de măsură a intensităţii câmpului magnetic. [pr.: örsted] – Din fr. oersted. Trimis de oprocopiuc, 01.05.2004. Sursa: DEX 98 ﻿ OERSTED s.m. (fiz.) Unitate de măsură pentru intensitatea unui câmp magnetic, egală cu… …   Dicționar Român

• OErsted — ou Ørsted (Hans Christian) (1777 1851) physicien danois; il découvrit l existence du champ magnétique créé par un courant électrique (1820). ⇒OERSTED, subst. masc. PHYS., vieilli. Unité magnétique absolue d intensité de champ, définie par la… …   Encyclopédie Universelle

• Oersted — Oer sted, n. [After Hans Christian Oersted, Danish physicist.] (Elec.) The C. G. S. unit of magnetic reluctance or resistance, equal to the reluctance of a centimeter cube of air (or vacuum) between parallel faces. Also, a reluctance in which… …   The Collaborative International Dictionary of English

• oersted — (De H. C. Oersted, 1777 1851, físico danés). m. Fís. Unidad de intensidad de campo magnético en el Sistema Cegesimal, equivalente a 79,58 amperios por metro. (Símb. Oe) …   Diccionario de la lengua española

• oersted — [ʉr′sted΄] n. [after H. C. Oersted (1777 1851), Dan physicist] the basic unit of electromagnetic field strength in the CGS system, equal to a force of one dyne acting upon a unit magnetic pole in a vacuum (79.58 ampere turns per meter): abbrev.… …   English World dictionary

• Oersted [1] — Oersted, Hans Christian, Bruder des Vorigen, einer der berühmtesten neuern Naturforscher, geb. 1777, ward 1806 Professor der Physik, 1829 Rector der polytechnischen Schule in Kopenhagen, 1840 Conferenzrath, 1850 Geh. Conferenzrath; st. 1851.… …   Herders Conversations-Lexikon

• Oersted [2] — Oersted, Anders Sandöe, geb. 1778 zu Rudkjöbing, dän. Rechtsgelehrter u. Schriftsteller. 1841–48 Staatsminister, 1853–54 Ministerpräsident …   Herders Conversations-Lexikon

• Oersted — Hans Christian …   Scientists

• oersted — (izg. èrsted) m DEFINICIJA fiz. stara jedinica jakosti magnetskog polja (znak Oe) ETIMOLOGIJA prema danskom fizičaru H. C. Oerstedu (1777 1851) …   Hrvatski jezični portal

• Oersted — (De Ch. Oersted, físico danés.) ► sustantivo masculino FÍSICA Unidad de intensidad del campo magnético en la nomenclatura internacional. * * * oersted. (De H. C. Oersted, 1777 1851, físico danés). m. Fís …   Enciclopedia Universal