JEE Main & Advanced Physics Electrostatics & Capacitance Electric Lines of Force

(1) Definition : The electric field in a region is represented by continuous lines (also called lines of force). Field line is an imaginary line along which a positive test charge will move if left free.

(2) Properties of electric lines of force

(i) Electric field lines come out of positive charge and go into the negative charge.

(ii) Tangent to the field line at any point gives the direction of the field at that point.

(iii) Field lines never intersect each other.

(iv) Field lines are always normal to conducting surface.

(v) Field lines do not exist inside a conductor.

(vi) The electric field lines never form closed loops. (While magnetic lines of forces form closed loop)

(vii) The number of lines originating or terminating on a charge is proportional to the magnitude of charge i.e. \[|Q|\,\,\propto \] number of lines.  In the following figure \[|{{Q}_{A}}|\,>\,|{{Q}_{B}}|\]

(viii) If the lines of forces are equidistant and parallel straight lines the field is uniform and if either lines of force are not equidistant or straight line or both the field will be non uniform, also the density of field lines is proportional to the strength of the electric field.