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Quiz 7 - Earth as a Magnet
The Earth's magnetic field can be represented by a magnetic
dipole located at the Earth's center. The dipole model of the Earth is quite
good up to 4RE, where RE is the radius of the Earth.
(a) Write down the expression for the Earth's magnetic field
in spherical coordinate system assuming that the Earth's dipole moment M is
oriented along the z axis (i.e. we are working with geomagnetic coordinates).
(b) The Earth's magnetic field on the surface of the Earth
at the equator is ≈ 0.31 G. Calculate the magnetic field (magnitude and
direction) at the north and south magnetic poles. (1 G = 10-4 T).
(c) Calculate the magnitude of the dipole moment of the
Earth. Assume the radius of the Earth to be 6000km.
Solution:
Physics key words: spherical magnetic, dipole, moment, field, radii, poles, field lines, EM, prorogation.
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