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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]
On the dayside of Earth, the magnetic field is significantly compressed by the solar wind to a distance of approximately 65,000 kilometers (40,000 mi). Earth's bow shock is about 17 kilometers (11 mi) thick [ 12 ] and located about 90,000 kilometers (56,000 mi) from Earth. [ 13 ]
Geomagnetic secular variation refers to changes in the Earth's magnetic field on time scales of about a year or more. These changes mostly reflect changes in the Earth's interior, while more rapid changes mostly originate in the ionosphere or magnetosphere. [1] The geomagnetic field changes on time scales from milliseconds to millions of years.
The condition governing this position is that the dynamic ram pressure from the solar wind is equal to the magnetic pressure from the Earth's magnetic field: [note 1] (()) where and are the density and velocity of the solar wind, and B(r) is the magnetic field strength of the planet in SI units (B in T, μ 0 in H/m).
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.
Thousands of years ago, Earth’s magnetic field underwent a significant power surge over a part of the planet that included the ancient kingdom of Mesopotamia. People at the time probably never ...
A magnetic field (sometimes called B-field [1]) is a physical field that describes the magnetic influence on moving electric charges, electric currents, [2]: ch1 [3] and magnetic materials. A moving charge in a magnetic field experiences a force perpendicular to its own velocity and to the magnetic field.
A mysterious radio blast from space detected in 2022 originated in the magnetic field of an ultra-dense neutron star 200 million light years away.. Known as fast radio bursts, or FRB, such brief ...