Electric Field Lines

Electric field (E) at a point is the force experienced by a unit positive test charge placed there: E = F/q₀.

Coulomb's Law: F = kq₁q₂/r², where k = 9 × 10⁹ N·m²/C² = 1/(4πε₀).

Field lines originate from positive charges and terminate on negative charges. They never cross.

The density of field lines indicates field strength — closer lines mean stronger field.

Electric field due to a point charge: E = kq/r², directed radially outward for +q, inward for −q.

Superposition principle: The net field at a point is the vector sum of fields due to individual charges.

In a uniform field, field lines are parallel and equally spaced.

At the surface of a conductor, the electric field is always perpendicular to the surface.