Transcript Day 17: Equipotential Surfaces

Day 17: Equipotential Surfaces
• Lines of equal potential
• Equipotential Surfaces
• Justification for Perpendicularity to the Electric Field
• Mapping of Equipotential Surfaces
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
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
Justification of Perpendicularity to the
Electric Field
• V    E  dl   E  dl cos  by def : A  B  A  B cos
• 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°,  E is  d l
• 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