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The magnetic field is generated by a feedback loop: current loops generate magnetic fields (Ampère's circuital law); a changing magnetic field generates an electric field (Faraday's law); and the electric and magnetic fields exert a force on the charges that are flowing in currents (the Lorentz force). [58]
Earth's_magnetic_field,_schematic.png (566 × 503 pixels, file size: 96 KB, MIME type: image/png) This is a file from the Wikimedia Commons . Information from its description page there is shown below.
The magnetic field of larger magnets can be obtained by modeling them as a collection of a large number of small magnets called dipoles each having their own m. The magnetic field produced by the magnet then is the net magnetic field of these dipoles; any net force on the magnet is a result of adding up the forces on the individual dipoles.
The three plot lines show the total field strength (blue), radial (vertical) field component (magenta) and the horizontal (south to north) field component (yellow). Field strengths are given in microteslas and the geographic latitude is given in degrees. The field strength reaches up to around 60 microteslas at the poles.
The magnetic field partially shields the Earth from harmful charged particles emanating from the Sun. The field is stretched back away from Sun by solar particles and radiation pressure. The geomagnetic field is generated (and regenerated) as the conducting fluid of the Earth's mantle and core, driven by convection of heat from deeper in the ...
The magnetic field of a magnetic dipole has an inverse cubic dependence in distance, so its order of magnitude at the earth surface can be approximated by multiplying the above result with (R outer core ⁄ R Earth) 3 = (2890 ⁄ 6370) 3 = 0.093 , giving 2.5×10 −5 Tesla, not far from the measured value of 3×10 −5 Tesla at the equator.
“The rumbling of Earth’s magnetic field is accompanied by a representation of a geomagnetic storm that resulted from a solar flare on November 3rd, 2011, and indeed it sounds pretty scary."
A time-varying magnetic field external to the Earth induces telluric currents—electric currents in the conducting ground. These currents create a secondary (internal) magnetic field. As a consequence of Faraday's law of induction, an electric field at the surface of the Earth is induced associated with time variations of the magnetic field ...