Q.Explain why the Earth behaves approximately like a short bar magnet, and describe how the angle of dip varies from the magnetic equator (where it is zero) to a magnetic pole (where it is $90^\circ$).

A freely suspended compass needle anywhere on Earth settles in a fixed direction, exactly as it would near a fixed magnet -- direct evidence of a persistent Earth field. The observed pattern of this field over the whole globe matches, to good approximation, that of a single short but powerful bar magnet located near the Earth's centre and tilted about $11.3^\circ$ from the rotation axis (Section 1.13), rather than any more complicated source. …

State the bar-magnet model for the Earth's field, then describe how the angle of dip changes moving f …

• Confusing the GEOGRAPHIC poles/equator with the MAGNETIC poles/equator -- they are close but not ident …