Electric Field

Arrows indicate the direction of the electric field. A positive test charge accelerates in the field direction (tangent to the arrows), while a negative test charge accelerates opposite the field direction. Lines start on + charges and end on − charges; line density qualitatively reflects field strength.

Isolated charge: outward for +, inward for −.

Isolated Point Charge

A positive test charge accelerates outward from +; toward −.

positive negative
polarity: +
Two like charges: ++ repels; −− draws lines inward toward both.

Two Like Charges

Flip to switch ++ ↔ −−. Horizontal pair suppressed to reduce clutter.

positive negative
polarity: ++
Opposite charges: +− (flip to −+). Exterior fans are mirror-symmetric.

Two Unlike Charges

positive negative
polarity: +−
Uniform field: top + / bottom − (flip to top − / bottom +). Mid-line markers are just arrowheads.

Parallel Plates (Opposite Charges)

+ plate − plate
polarity: top + / bottom −