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The magnitude of Earth's magnetic field at its surface ranges from 25 to 65 μT (0.25 to 0.65 G). [3] As an approximation, it is represented by a field of a magnetic dipole currently tilted at an angle of about 11° with respect to Earth's rotational axis, as if there were an enormous bar magnet placed at that angle through the center of Earth.
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 spacing between field lines is an indicator of the relative strength of the magnetic field. Where magnetic field lines converge the field grows stronger, and where they diverge, weaker. Now, it can be shown that in the motion of gyrating particles, the "magnetic moment" μ = W ⊥ /B (or relativistically, p ⊥ 2 /2mγB) stays very nearly ...
Study of Earth's magnetosphere began in 1600, when William Gilbert discovered that the magnetic field on the surface of Earth resembled that of a terrella, a small, magnetized sphere. In the 1940s, Walter M. Elsasser proposed the model of dynamo theory, which attributes Earth's magnetic field to the motion of Earth's iron outer core.
The electric and magnetic fields in such a wave are in-phase with each other, reaching minima and maxima together. Electric and magnetic fields obey the properties of superposition. Thus, a field due to any particular particle or time-varying electric or magnetic field contributes to the fields present in the same space due to other causes.
Unlike the geographic North Pole, which marks a fixed location, the magnetic north pole’s position is determined by Earth’s magnetic field, which is in constant motion. Over the past few ...
Additional magnetic field values can be found through the magnetic field of a finite beam, for example, that the magnetic field of an arc of angle and radius at the center is =, or that the magnetic field at the center of a N-sided regular polygon of side is = , both outside of the plane with proper directions as inferred by right hand ...
New research indicates the sun’s magnetic field originates much closer to the surface than previously thought, a finding that could help predict periods of extreme solar storms like the ones ...