Electric lines of force
The concept of field lines was introduced by Michael Faraday as
an aid in visualizing electric and magnetic fields.
Electric line of force is an imaginary straight or curved path along
which a unit positive charge tends to move in an electric field.
The electric field due to simple arrangements of point charges are
shown below
Properties of lines of forces:
(i) Lines of force start from positive charge and terminate at negative
charge.
(ii) Lines of force never intersect.
(iii) The tangent to a line of force at any point gives the direction of
the electric field (E) at that point.
(iv) The number of lines per unit area, through a plane at right angles
to the lines, is proportional to the magnitude of E. This means
that, where the lines of force are close together, E is large and
where they are far apart, E is small.