Coulomb’s force describes the direct interaction between two charges, but there is a more general and powerful way of thinking about this interaction: every charge generates an electric field in the surrounding space, and other charges feel the force precisely through this field. This idea, due to Michael Faraday, shifts the attention from the pair of charges to space itself, which becomes the physical protagonist.
This section introduces the definition of the electric field, the visual paradigm of field lines with its five rules, the quantitative method for finding the strength from the line density, the concept of the equipotential surface, and finally the two complementary strategies for calculating the field at a point.
- What is the electric field?
- Field lines: the five rules
- Counting the lines: the field from density
- Equipotential surfaces
- Two ways to calculate the field
Try it — electrostatics simulator
Place charges and watch field lines and equipotential surfaces: the electric field made visible.