1. Day 17: Equipotential Surfaces
Lines of equal potential
Equipotential Surfaces
Justification for Perpendicularity to the Electric Field
Mapping of Equipotential Surfaces

2. Equipotential Lines
A line in which all points are at the same voltage, is called an equipotential line.
Equipotential Lines are perpendicular to the electric field

3. Equipotential Surfaces
A surface in which all points are at the same voltage is called an equipotential surface
An equipotential surface
must be perpendicular to
the electric field

4. Justification of Perpendicularity to the Electric Field
On a surface where V is constant, ΔV = 0, so either E = 0, or dl = 0, or cosθ = 0 (where cosθ is the angle between E & dl). For cosθ = 0, θ = 90°,
On a surface of a conductor of uniform charge, the entire surface is an equipotential surface, otherwise free electrons on the surface would move through the potential difference