Comments on the Motion of Magnetic Field Lines
2006 (English)In: American Journal of Physics, ISSN 0002-9505, E-ISSN 0002-9595, Vol. 74, no 5, 454-455 p.Article in journal (Other academic) Published
Belcher and Olbert recently showed that the concept of the motion of magnetic field lines can behelpful in teaching classical electromagnetism. Although this concept holds in many situations, ithas important limitations. It is shown that the most common definition, v=EB/B2, which is theone used by Belcher and Olbert, is not appropriate when an electrostatic field is present, unless thefield satisfies special conditions. In an infinitely conducting medium where the electric field has nocomponent parallel to the magnetic field, EB/B2 is still a meaningful definition of the motion ofmagnetic field lines which follow the plasma motion as if “frozen-in”. It used to be assumed thatspace plasmas could be treated as infinitely conducting and therefore the concept of magnetic fieldline motion was used extensively. But local nonvanishing values of E·B can “cut” magnetic fieldlines and invalidate the frozen-in condition.
Place, publisher, year, edition, pages
2006. Vol. 74, no 5, 454-455 p.
IdentifiersURN: urn:nbn:se:kth:diva-77688DOI: 10.1119/1.2180285ISI: 000237366700019ScopusID: 2-s2.0-33646880246OAI: oai:DiVA.org:kth-77688DiVA: diva2:491950
QC 201202222012-02-072012-02-072012-02-22Bibliographically approved