🔷 Field of an Electric Dipole

📖 The Physics

A dipole's field points away from the +q charge and into the −q charge. Two special lines matter most: the axial line (the line through both charges) and the equatorial line (the perpendicular bisector).

Move the green test point with the angle slider and compare the exact field with the standard formulas for these two directions.

Set θ = 0° (axial) and θ = 90° (equatorial): the axial field is about twice as strong at the same distance. Both fall off as 1/r³— much faster than a single charge's 1/r², because the two charges nearly cancel far away. (The formulas assume r ≫ a.)