Which quantity is not a vector (i.e., is scalar)?

• A. Electric potential
• B. Electric field
• C. Velocity
• D. Displacement

Answer: (A)

Vectors have both size and direction, while scalars have only size. Electric potential fits the scalar idea: at each point it assigns a single number—the potential energy per unit charge—without any direction.

In contrast, the electric field has a direction and a magnitude, describing the force a unit positive test charge would feel at that point. Velocity is how fast and in which direction an object moves, and displacement is the overall change in position with a direction. All of these are vector quantities, so they require both magnitude and direction to specify them.

There’s also a direct connection between potential and field: the electric field is the negative gradient of the potential, E = -∇V. That relationship shows how a scalar field (V) gives rise to a vector field (E).