Magnetic induction

From Glossary of Meteorology



magnetic induction

A vector field, usually denoted by B, defined as follows.

The torque N experienced by a magnetic dipole with magnetic dipole moment m is
ams2001glos-Me1
Thus by measuring N for m oriented in two orthogonal directions, the magnetic induction components are obtained as torque components divided by the magnitude of m. The fundamental relation linking electric field E and magnetic induction B to the force on a charge q with velocity v is the Lorentz force equation
ams2001glos-Me2
Magnetic induction is sometimes called magnetic field, a term usually applied to a different field H, related to B but different from it. In free space, B and H are proportional:
ams2001glos-Me3
where μ0, the permeability of free space, is a universal constant. B is the primitive field, whereas H is secondary, not strictly needed but convenient. Care must be exercised in deciding if, by magnetic field, B or H is meant. What is usually meant by the electric and magnetic fields (or the electromagnetic field) are E and H, although according to the Lorentz force equation E and B are the fundamental fields. Moreover, the Lorentz transformation preserves the (E, B) structure but not the (E, H) structure.


Copyright 2022 American Meteorological Society (AMS). For permission to reuse any portion of this work, please contact permissions@ametsoc.org. Any use of material in this work that is determined to be “fair use” under Section 107 of the U.S. Copyright Act (17 U.S. Code § 107) or that satisfies the conditions specified in Section 108 of the U.S.Copyright Act (17 USC § 108) does not require AMS’s permission. Republication, systematic reproduction, posting in electronic form, such as on a website or in a searchable database, or other uses of this material, except as exempted by the above statement, require written permission or a license from AMS. Additional details are provided in the AMS Copyright Policy statement.