Oersted (Unit)

Introduction

The Oersted (Oe) is a unit of magnetic field strength in the centimeter-gram-second (CGS) system of units. Named after the Danish physicist Hans Christian Ørsted, this unit has been widely used in the field of magnetism.

Definition and Measurement

Magnetic Field Strength

Magnetic field strength, also known as magnetic field intensity, is a measure of the magnetizing force, or the amount of magnetic field produced by a current flowing through a coil of wire. In the CGS system, this quantity is measured in Oersteds.

Oersted

One Oersted is defined as the magnetic field strength in a vacuum produced by a current of one abampere per centimeter of length. Mathematically, this can be written as:

In SI units, the Oersted is a non-standard unit. The corresponding SI unit for magnetic field strength is the Ampere per meter (A/m). The conversion between Oersteds and Ampere per meter is:

Importance and Usage of the Oersted

The Oersted is used to measure the strength of the magnetizing field in a material. It plays a crucial role in understanding and designing magnetic materials and devices. Despite being a non-SI unit, it is still widely used, especially in the United States, in industries and scientific research related to magnetism.

Quantities Associated with the Oersted

Magnetic Flux Density (B-field)

While the Oersted is used to measure the magnetic field strength (H-field), another important quantity is the magnetic flux density (B-field), which is measured in Gauss in the CGS system, or Tesla in the SI system. The relationship between B-field and H-field depends on the material’s magnetic permeability.

Magnetic Permeability

Magnetic permeability is a measure of how easily a magnetic field can penetrate a material. It relates the magnetic field strength (H) and the magnetic flux density (B) as:

where is the magnetic permeability. In a vacuum, is the permeability of free space , and and are proportional.

Oersted’s Experiment

Hans Christian Ørsted is famous for discovering that electric currents create magnetic fields, an essential concept in electromagnetism. His simple yet ground-breaking experiment involving a compass needle deflected by a current-carrying wire paved the way for the development of electromagnetic theory.

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