Equipotential surfaces Electric Fields Coulomb’s law The electric field Electric field lines Electric potential Equipotential surfaces
Coulomb’s Law The SI unit of charge is the coulomb (C) ke is called the Coulomb constant ke = 8.9875 x 109 N.m2/C2 = 1/(4πo) o is the permittivity of free space o = 8.8542 x 10-12 C2 / N.m2
The electric field The electric field vector, E, at a point in space is defined as the electric force F acting on a positive test charge, qo placed at that point divided by the test charge: E = Fe / qo
Electric field lines
Electric potential The electric potential is The potential is a scalar quantity Since energy is a scalar As a charged particle moves in an electric field, it will experience a change in potential
Equipotential Surfaces The equipotential surfaces must always be perpendicular to the electric field lines passing through them. A point charge An electric dipole Infinite sheet of charge