4.1 Basic Outline

At the heart of the planet is an enormous magnetic core that gives the Earth’s navigators a useful reference. The lines of magnetic force run from south to north and these provide a reference for our compasses.

To fully define the Earth’s Magnetic Field at any location, we need three components of a vector. The Field Strength, usually measured in nano Teslas or micro Teslas, the Declination Angle defined as the True Direction of Magnetic North and the Dip Angle defined as the vertical dip of the Earth vector below horizontal. For computing reasons, this vector is often defined as three orthogonal magnetic field components pointing towards True North, East, and vertical referred to as Bn, Be and Bv. A fundamental law of physics relating magnetic field strength to electric current is known as the Biot-Savart Law and this is our best explanation for why B is used to denote magnetic field strength. If you know better, please contact the author (feedback below).