Q. 23

# Assume the dipole model for earth’s magnetic field B which is given by B_{V} = vertical component of magnetic field _{}

B_{H} = Horizontal component of magnetic field _{}

Θ = 90° – latitude as measured from magnetic equator.

Find loci of points for which (i) B is minimum; (ii) dip angle is zero; and (iii) dip angle is ± 45°.

Answer :

… The vertical component of earth’s magnetic field

… horizontal component of earth’s magnetic field

Net magnetic field B =

For the above equation, the minimum value occurs when , as cos() = 0

Thus B is minimum at the magnetic Equator

Angle of dip(

When

The locus where =0 is again the magnetic equator

(iii)

or

Thus is the locus of points with .

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