A visual representation of the electric field can be obtained in term of electric field lines; an idea proposed by Michael faraday. Electric field lines can be thought of a “map” that provides information about the direction and strength of electric field at various places. As electric field lines provide information about the electric force exerted on a charge, the lines are commonly called “lines of force”.

To introduce electric field lines, we place positive test charges each of magnitude at different places but at equal distances from a positive charge +q as show in the figure.

Each test charge will experience a repulsive force as indicated by arrow. Therefore the electric field created by the charge +q is directed radially outward as shown in the figure     

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Corresponding field lines show the field direction. The electric field lines of a negative charge are directed radially inward, because the force on the positive test charge is know of attraction, indicating the electric field points inward.

Electric field lines emerge from the charges in three dimensions, and an infinite number of lines could be drawn.