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Why do electric field lines point outward from a positive charge?

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In physics, the direction of an electric field is defined by the force that would be exerted on a positive test charge placed within that field. Because like charges repel one another, a positive test charge placed near an isolated positive source charge will experience a repulsive force, pushing it radially away from the source.12

Consequently, the electric field lines around a positive charge are oriented to point outward. These field lines serve as a visual representation of the field's direction and magnitude; they are drawn as continuous lines originating from positive charges, which act as sources, and terminating on negative charges. The density of these lines at any given point provides a measure of the field's strength, with closer lines indicating a stronger field.13