Illustration for conceptualizing voltage near a point charge

Conceptualizing the voltage near a point charge.

Electrostatics is the field describing the behavior of charges interacting through the electric force, the force described by Coulomb's Law, which, unlike magnetic force, may occur between stationary charges. We can describe the force between two charges, Charge X and Charge Y, or we might choose to describe the electric field permeating the space surrounding Charge X alone. The electric field of Charge X describes its ability to exert force on any other charge in its vicinity. The electric field tells us how many Newtons of force would be exerted per Coulomb of charge were charge placed at the particular location of the field under discussion. So, with regard to point charges, the description of force applies to a specific interaction between two or more charges while the field describes the ability of one charge to exert force, an ability that permeates the space around it.

An analogy to this relationship between electric force and electric field extends to the relationship between potential energy and electric potential or voltage. We can describe either the specific electrical potential energy state existing between Charge X and Charge Y or we can describe the energy properties of the field of Charge X alone. If we are talking about electric potential or voltage, we ask how hard would it be to do work against this field if we were to move a hypothetical charge from one position to another in the field? How many joules of work does it take to move a Coulomb of hypothetical charge (joules/Coulomb = Volts) from infinitely far away to Point A near Charge X. This is the electric potential of Point A. The joules per Coulomb required to move from Point A to Point B gives the potential difference, or voltage, between these points. So the description of potential energy applies to a specific arrangement of two or more charges while the voltage describes the ability of the field to perform work on hypothetical charges we imagine moving around in the field.

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