Electric Fields and Electric Field Lines

Electric Field

Electric field is a region in space where a charge experiences force from another charge.
It's a region where the force effect is present.

Electric field lines represent the electric field produced by a charged particle.
They are lines of force.
The direction of the electric field is the direction a positive charge would move if placed in the field.
Electric field lines help visualize the vector nature of the electric field.

Electric field lines do not cross each other.
Electric field lines originate from positive charges and terminate on negative charges.
The lines are perpendicular to the charged surface.
The closer the lines, the stronger the electric field; the farther apart, the weaker the field.
The electric field between two parallel plates shows a uniform electric field.
Electric field lines move away from positive charges and towards negative charges.
A tangent drawn at any point on an electric field line gives the direction of the field at that point.
The electric field cannot have two directions at a particular point; hence, field lines never intersect.
The magnitude of charge and the number of field lines are proportional to each other. A larger charge will have more electric field lines.
Electric field lines enter or exit a charged surface in a normal (perpendicular) manner.
In a uniform electric field, the field lines are uniformly spaced and parallel.
The electric field lines are perpendicular (orthogonal) to the surface of the charged object.

Electric field lines cannot go through a conductor.
Inside a conductor in electrostatic equilibrium, the electric field is zero.
Electric field lines tend to contract in length due to the force of attraction between oppositely charged objects.
Electric lines of force tend to separate from each other laterally (perpendicular to their lengths).

When a conductor is placed in an external electric field, a force acts on each free electron:
F = qE where q is the charge and E is the electric field.
"So, F = -eE acts on each free electron" where e is the electron.
Electrons accumulate on one side of the conductor, creating opposing charges (negative and positive) on opposing sides.
These separated charges produce their own electric field, which opposes the external field inside the conductor.
When enough electrons accumulate, the electric field produced by the separated charges cancels the external field inside the conductor.
In electrostatic equilibrium, the electric field inside a conductor is zero.

When placed in an electric field, insulators have practically no current flow because they lack loosely bonded free electrons.
Positive charges within the electric field are displaced slightly in the direction of the electric field, and negative charges are displaced in the opposite direction.
This slight charge separation is called polarization and reduces the electric field within the dielectric.
An insulator placed in a static electric field will weaken the field.