Oersted (unit): Difference between revisions
imported>Paul Wormer No edit summary |
imported>Paul Wormer No edit summary |
||
| Line 1: | Line 1: | ||
{{subpages}} | {{subpages}} | ||
The '''oersted''' (abbreviated as Oe) is the unit of [[magnetic field]] strength |'''H'''| in the | The '''oersted''' (abbreviated as Oe) is the unit of [[magnetic field]] strength |'''H'''| in the | ||
cgs-emu (centimeter-gram-second electromagnetic unit) | cgs-emu (centimeter-gram-second electromagnetic unit) and Gaussian systems of units. The field strength in a point in vacuum is 1 Oe if a unit magnetic pole in the point experiences a force of 1 [[dyne]] ( = 1⋅10<sup>−5</sup> newton). | ||
The [[Biot-Savart law#Magnetic field on axis of circular current|Biot-Savart law]] | |||
in Gaussian units, for which in vacuum '''B''' = '''H''', states that the field in the center of a conducting loop of radius ''r'' is, | |||
:<math> | |||
|\mathbf{H}| = \frac{2\pi i}{c r}, | |||
</math> | |||
where ''c'' is speed of light. Hence, one may alternatively define the Gaussian unit ''oersted'' as the magnetic field strength |'''H'''| in the center of a conducting loop with radius of 1 cm, carrying an electric current ''i'' of 1/(2π) ampere. Note here that ampere/''c'' (the ''statampere'') is the unit of current and the centimeter is the unit of length in the Gaussian system of units. | |||
One oersted equals 1000/4π A/m (ampere per meter, which is the [[SI]] unit for |'''H'''|). | One oersted equals 1000/4π A/m (ampere per meter, which is the [[SI]] unit for |'''H'''|). | ||
The oersted is named after the Danish physicist [[Hans Christian Oersted]]. Before 1932 the oersted was known as gauss, a name sometimes still applied, though now more properly used for the cgs-emu unit of strength of [[magnetic induction]] |'''B'''|. | The oersted is named after the Danish physicist [[Hans Christian Oersted]]. Before 1932 the oersted was known as gauss, a name sometimes still applied, though now more properly used for the cgs-emu and Gaussian unit of strength of [[magnetic induction]] |'''B'''|. | ||
Revision as of 09:40, 24 May 2008
The oersted (abbreviated as Oe) is the unit of magnetic field strength |H| in the cgs-emu (centimeter-gram-second electromagnetic unit) and Gaussian systems of units. The field strength in a point in vacuum is 1 Oe if a unit magnetic pole in the point experiences a force of 1 dyne ( = 1⋅10−5 newton).
The Biot-Savart law in Gaussian units, for which in vacuum B = H, states that the field in the center of a conducting loop of radius r is,
where c is speed of light. Hence, one may alternatively define the Gaussian unit oersted as the magnetic field strength |H| in the center of a conducting loop with radius of 1 cm, carrying an electric current i of 1/(2π) ampere. Note here that ampere/c (the statampere) is the unit of current and the centimeter is the unit of length in the Gaussian system of units.
One oersted equals 1000/4π A/m (ampere per meter, which is the SI unit for |H|).
The oersted is named after the Danish physicist Hans Christian Oersted. Before 1932 the oersted was known as gauss, a name sometimes still applied, though now more properly used for the cgs-emu and Gaussian unit of strength of magnetic induction |B|.