3.7.2.3
Equipotential surfaces are perpendicular to field lines
Gravitational Fields & Orbits — AQA A-Level Physics
Key Definition
Equipotential surface — A surface joining points that all have the same gravitational potential. No work is done moving along an equipotential.
- Equipotential lines are always perpendicular to the field lines.
- They are drawn as dashed lines (field lines are solid with arrows).
- In a radial field: equipotentials are concentric circles, getting further apart with distance from the mass.
- In a uniform field: equipotentials are horizontal, parallel, and equally spaced.
- Moving along an equipotential: $\Delta V = 0$, so no work is done. An object travelling along an equipotential neither gains nor loses energyThe capacity to do work. Measured in joules (J)..
Examiner Tips and Tricks
- Equipotential lines must not have arrows on them.
- They have no direction and are not vectors.
- Draw them with a ruler as dashed lines.