The electric field. Charge distribution on conductors

Charged bodies interact without touching; Faraday explained this by the electric field: every charge has a field around it, and the field acts with a force on other charges. The field of stationary charges is called the electrostatic field; it weakens as we move away from the charge. We cannot see the field, so we draw field lines: they start on a positive charge and end on a negative charge (or at infinity). To judge the field at a point, a small positive test charge q₀ is placed there: the field strength is E = F/q₀, measured in N/C, directed like the force on a positive charge (a vector quantity). At a distance r from a point charge q in a vacuum, E = k·|q|/r². In a dielectric the field is ε times weaker: E = k·|q|/(ε·r²), where ε is a dimensionless quantity (ε = 1 for a vacuum).