The correct and unusual coordinate transformation rules for electromagnetic quadrupoles

Gratus, Jonathan and Banaszek, Thomas (2018) The correct and unusual coordinate transformation rules for electromagnetic quadrupoles. Proceedings of the Royal Society A: Mathematical, Physical and Engineering Sciences, 474 (2213). ISSN 1364-5021

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Abstract

Despite being studied for over a century, the use of quadrupoles have been limited to Cartesian coordinates in flat spacetime due to the incorrect transformation rules used to define them. Here the correct transformation rules are derived, which are particularly unusual as they involve second derivatives of the coordinate transformation and an integral. Transformations involving integrals have not been seen before. This is significantly different from the familiar transformation rules for a dipole, where the components transform as tensors. It enables quadrupoles to be correctly defined in general relativity and to prescribe the equations of motion for a quadrupole in a coordinate system adapted to its motion and then transform them to the laboratory coordinates. An example is given of another unusual feature: a quadrupole which is free of dipole terms in polar coordinates has dipole terms in Cartesian coordinates. It is shown that dipoles, electric dipoles, quadrupoles and electric quadrupoles can be defined without reference to a metric and in a coordinates free manner. This is particularly useful given their complicated coordinate transformation.

Item Type: Journal Article
Journal or Publication Title: Proceedings of the Royal Society A: Mathematical, Physical and Engineering Sciences
Uncontrolled Keywords: /dk/atira/pure/subjectarea/asjc/2600
Subjects:
Departments: Faculty of Science and Technology > Physics
ID Code: 124494
Deposited By: ep_importer_pure
Deposited On: 12 Apr 2018 13:36
Refereed?: Yes
Published?: Published
Last Modified: 16 Feb 2020 04:32
URI: https://eprints.lancs.ac.uk/id/eprint/124494

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