Let the magnetic field on earth be modeled by that of a point magnetic dipole at the center of earth. The angle of dip at a point on the geographical equator

The angle of dip is the angle formed between the magnetic axis and the geographical axis of the earth. The angle can be positive as well as negative, positive angle defines that the magnetic field is pointing downward where negative is vice versa. Now the magnetic dip is only zero (nearly zero) at the equator because the magnetic lines of force are horizontal. Thus, the value ranges from to .