Electric Field Lines
Place charges in space and watch electric field lines form in real time. Understand superposition and field behavior visually.
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.
Coulomb's Law
Force between two point charges.
Electric Field (point charge)
Field magnitude at distance r from charge q.
Field Due to Dipole (axial)
On the axis of a dipole, far from it.
Field Due to Dipole (equatorial)
On the perpendicular bisector of a dipole.
Dipole Moment
Product of charge and separation distance.
Force on Charge in Field
Force on charge q in electric field E.
Electric field inside a conductor in electrostatic equilibrium is ZERO.
Field lines are perpendicular to equipotential surfaces.
A dipole in a uniform field experiences torque τ = pE sinθ but zero net force.
A dipole in a non-uniform field experiences both torque and a net force.
The number of field lines from a charge is proportional to the magnitude of the charge.
In JEE, superposition + symmetry arguments simplify complex charge distribution problems.