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.

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.

It creates an electric potential difference.

Electrons flow from the negative terminal (anode) to the positive terminal (cathode) through an external circuit.

The potential difference between the plates doubles, assuming the charge remains constant.

The electric potential decreases.

The electric potential increases.