Fernández-Rañada, Antonio2023-06-202023-06-201997-07-210375-960110.1016/S0375-9601(97)00366-6https://hdl.handle.net/20.500.14352/58981© 1997 Elsevier Science BV. We are grateful to Professors M.V. Berry, A. Dobado, A. Ibort, E. López, J.M. Montesinos, M. Soler and J.L. Vicent for discussions and encouragement and to Professor A. Tiemblo for hospitality to A.F.R. at the Instituto de Matemáticas y Física Fundamental, CSIC, Madrid.We prove two properties of the electromagnetic knots in empty space. First, that any standard radiation fields (i.e. satisfying E . B = 0) coincide locally with an electromagnetic knot. Second, that the electric and magnetic helicities of any knot are equal. These results can be used as a basis for a topological model of electromagnetism.engjournal articlehttp://dx.doi.org/10.1016/S0375-9601(97)00366-6http://www.sciencedirect.comrestricted access537Electromagnetic FieldTopological FieldKnotHelicityLink.ElectricidadElectrónica (Física)2202.03 Electricidad