Electric potential: Electric potential energy per unit charge. | Electric potential energy: Energy a charge possesses due to its location in an electric field.

Single point charge: $V=\frac{q}{4 \pi \varepsilon_{0} r}$ | Multiple point charges: $V=\frac{1}{4 \pi \varepsilon_{0}} \sum_{i} \frac{q_{i}}{r_{i}}$

Electric field lines: Indicate the direction of the electric force on a positive charge. | Equipotential lines: Connect points of equal electric potential; perpendicular to electric field lines.

Closely spaced isolines: Correspond to a strong electric field. | Widely spaced isolines: Indicate a weak electric field.

Anode: Negative terminal, electrons flow from here. | Cathode: Positive terminal, electrons flow to here.

Use scalar superposition: $V=\frac{1}{4 \pi \varepsilon_{0}} \sum_{i} \frac{q_{i}}{r_{i}}$. Sum the potential contributions from each individual charge.

Use integration, breaking the distribution into infinitesimal point charges $dq$ and summing their contributions.

Batteries use redox reactions to create a potential difference between their terminals.

Integrate the dot product of the electric field ($\vec{E}$) and the displacement ($d\vec{r}$) along any path: $\Delta V=V_{b}-V_{a}=-\int_{a}^{b} \vec{E} \cdot d \vec{r}$.

The electric field points in the direction of the steepest decrease in electric potential.

Electric potential is the electric potential energy per unit charge at a point in space.

Volts (V), where 1 V = 1 joule per coulomb (J/C).

The electric potential difference ($\Delta V$) is the change in electric potential energy ($Delta U_E$) per unit charge when moving a test charge between two points: $\Delta V = \frac{\Delta U_E}{q}$.

Equipotential lines, also called isolines, connect points of equal electric potential.

Permittivity of free space ($epsilon_0$) is a physical constant that describes the ability of a vacuum to permit electric fields.