Final answer:
The electric potential is the amount of electric potential energy per unit charge, often represented by the equation V = kQ/r. The electric potential is constant on equipotential lines or surfaces, and it is a scalar quantity.
Step-by-step explanation:
The quantity that represents the electric potential is the amount of electric potential energy per unit charge at a specific point in space. This is commonly referred to as the potential or voltage. The equipotential line or surface is a useful concept in visualizing this, as it represents all points where the electric potential is the same. Specifically, the potential for a point charge is represented by the equation V = kQ/r, where V is the potential, k is Coulomb's constant, Q is the charge, and r is the radius or distance from the charge. Therefore, the potential is constant at any point that is the same distance r from a charge. This concept is important when analyzing electric fields and understanding the force that a charge would experience in different positions relative to other charges, as reflected in diagrams like Figure 19.8 or 19.12.
When considering how to measure the electric potential or set up experiments dealing with electrical charges, one must take into account that electric field lines are perpendicular to equipotential lines and that the potential is a scalar quantity, meaning it has magnitude but no direction, as opposed to a vector such as the electric field.