How do we obtain I-Biot-Sawart? We consider a point on a model whereby the size and permeability are those of the Earth.
Permeability of the medium material
between P,P1 and globe rotation axis: As we are working with Earth model,
therefore we suppose the permeability as one of Earth, the average
of Iron (99.95%) (Because Earth core is assumed as Iron), and normal air (µ0
=4π*10-7N/A2).
So we have:
µ=1/2 (0.25+4π*10-7) =0.12500126 N/A2
General formula for speed (v) of P: v=2πr/24*60*60 m/s, replace ‘’v’’ to Biot-Savart
expression, we have :
dB=7.233869*10-7*q/r
(named as I-Biot-Savart).
Although the coefficient 7.233869*10-7 is derived from µ, π and cycle (24 hrs), it is interpolated from Biot-Savart expression, so we name it as ‘’ interpolated Biot-Savart’’ or I-Biot-Savart for further reference.
