3.7.3.3
Equipotential surfaces are perpendicular to field lines
Electric Fields & Potential — AQA A-Level Physics
Key Definition
Equipotential surface — A surface joining points that have the same electric potential. No work is done when a charge moves along an equipotential surface.
- Equipotential lines are always perpendicular to field lines.
- They are drawn as dotted lines (field lines are solid with arrows).
- Around a point chargeA property of matter that causes it to experience a force in an electromagnetic field. Measured in coulombs (C).: equipotential lines are concentric circles, getting further apart with distance.
- Between parallel plates: equipotential lines are equally spaced parallel lines.
- Between two opposite charges: a central equipotential line at 0 V exists where the opposing potentials cancel.
- Between two like charges: a neutral point between them where the resultant field is zero.
- The spacing between equipotential lines indicates field strength. Closer $spacing = stronger field$.
Examiner Tips and Tricks
- Equipotential lines have no arrows because they are not vectors.
- They show where the potential is the same, not a direction.