Answer the following question regarding earth:
The earth's field, it is claimed, roughly approximates the field due to a dipole of magnetic moment 8 x 1022 J T–1 located at its centre. Check the order of magnitude of this number in some way.
Magnetic field B at an equatorial point of the earth's magnetic dipole is given by
Now,
Therefore,
Which is of the same order of magnitude as that of the observed field on the earth.
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