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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.
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.
The dipole model of the Earth's magnetic field is a first order approximation of the rather complex true Earth's magnetic field. Due to effects of the interplanetary magnetic field (IMF), and the solar wind , the dipole model is particularly inaccurate at high L-shells (e.g., above L=3), but may be a good approximation for lower L-shells.
The definitions for monopoles are of theoretical interest, although real magnetic dipoles can be described using pole strengths. There are two possible units for monopole strength, Wb (Weber) and A m (Ampere metre). Dimensional analysis shows that magnetic charges relate by q m (Wb) = μ 0 q m (Am).
Magnetic induction B (also known as magnetic flux density) has the SI unit tesla [T or Wb/m 2]. [1] One tesla is equal to 10 4 gauss. Magnetic field drops off as the inverse cube of the distance ( 1 / distance 3 ) from a dipole source. Energy required to produce laboratory magnetic fields increases with the square of magnetic field. [2]
10 −6 –10 −3 G – the magnetic field of Galactic molecular clouds. Typical magnetic field strengths within the interstellar medium of the Milky Way are ~5 μG. 0.25–0.60 G – the Earth's magnetic field at its surface; 4 G – near Jupiter's equator; 25 G – the Earth's magnetic field in its core [4] 50 G – a typical refrigerator magnet
The magnetization field or M-field can be defined according to the following equation: =. Where is the elementary magnetic moment and is the volume element; in other words, the M-field is the distribution of magnetic moments in the region or manifold concerned.
The geomagnetic field strength and hence precession frequency varies with location and time. Larmor precession frequency = magnetogyric ratio x magnetic field Proton magnetogyric ratio = 42.576 Hz/μT (also written 42.576 MHz/T or 0.042576 Hz/nT) Earth's magnetic field: 30 μT near Equator to 60 μT near Poles, around 50 μT at mid-latitudes.