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  2. History of geomagnetism - Wikipedia

    en.wikipedia.org/wiki/History_of_geomagnetism

    The earliest ideas on the nature of magnetism are attributed to Thales (c. 624 BC – c. 546 BC). [1] [2] In classical antiquity, little was known about the nature of magnetism. No sources mention the two poles of a magnet or its tendency to point northward. There were two main theories about the origins of magnetism.

  3. Earth's magnetic field - Wikipedia

    en.wikipedia.org/wiki/Earth's_magnetic_field

    The remaining terms predict that the potential of a dipole source (ℓ=1) drops off as 1/r 2. The magnetic field, being a derivative of the potential, drops off as 1/r 3. Quadrupole terms drop off as 1/r 4, and higher order terms drop off increasingly rapidly with the radius. The radius of the outer core is about half of the radius of the Earth.

  4. Telluric current - Wikipedia

    en.wikipedia.org/wiki/Telluric_current

    A telluric current (from Latin tellūs 'earth'), or Earth current, [1] is an electric current that flows underground or through the sea, resulting from natural and human-induced causes. These currents have extremely low frequency and traverse large areas near or at Earth 's surface.

  5. Petrus Peregrinus de Maricourt - Wikipedia

    en.wikipedia.org/wiki/Petrus_Peregrinus_de_Maricourt

    Pivoting compass needle in a 14th-century handcopy of Peter's Epistola de magnete (1269). Petrus Peregrinus de Maricourt (Latin), Pierre Pelerin de Maricourt (French), or Peter Peregrinus of Maricourt [1] (fl. 1269), was a French mathematician, physicist, and writer who conducted experiments on magnetism and wrote the first extant treatise describing the properties of magnets.

  6. Terrestrial magnetism - Wikipedia

    en.wikipedia.org/?title=Terrestrial_magnetism&...

    This page was last edited on 13 July 2016, at 01:13 (UTC).; Text is available under the Creative Commons Attribution-ShareAlike 4.0 License; additional terms may ...

  7. Jefimenko's equations - Wikipedia

    en.wikipedia.org/wiki/Jefimenko's_equations

    Jefimenko says, "...neither Maxwell's equations nor their solutions indicate an existence of causal links between electric and magnetic fields. Therefore, we must conclude that an electromagnetic field is a dual entity always having an electric and a magnetic component simultaneously created by their common sources: time-variable electric ...

  8. Hockey player Matthew Petgrave crowdfunding for legal fees ...

    www.aol.com/hockey-player-matthew-petgrave-crowd...

    Canadian hockey player Matthew Petgrave has begun crowdfunding to help cover his legal fees in connection with the death of fellow hockey player Adam Johnson.

  9. K-index - Wikipedia

    en.wikipedia.org/wiki/K-index

    The official planetary K p-index is derived by calculating a weighted average of K-indices from a network of 13 geomagnetic observatories at mid-latitude locations.Since these observatories do not report their data in real-time, various operations centers around the globe estimate the index based on data available from their local network of observatories.