Difference between revisions of "Oersted (unit)"

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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) system 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&sdot;10<sup>&minus;5</sup> newton). The cgs-emu defining equation of the oersted is: Oe =
+
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&sdot;10<sup>&minus;5</sup> newton).  
cm<sup>&minus;1/2</sup> g<sup>1/2</sup> s<sup>&minus;1</sup>.
+
The oersted is also the unit of magnetic field strength in the system of [[Gaussian units]].
+
  
In agreement with the [[Biot-Savart law]] one may also define one oersted as the magnetic field strength |'''H'''| in the center of a conducting loop with radius of 1 cm, carrying a current of 10/(2&pi;) A.
+
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/(2&pi;) 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 &nbsp; (ampere per meter, which is  the [[SI]] unit for |'''H'''|).  
 
One oersted equals 1000/4π A/m &nbsp; (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 14:40, 24 May 2008

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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|.