Final answer:
The electric potential inside a capacitor is associated with the charge and voltage it carries, relating to the electrical potential energy stored. The energy can be calculated by taking the average voltage experience during charging, which gives the formula Ecap = 1/2 QV. Additionally, a capacitor's potential difference is equivalent to an emf only when no current is drawn or supplied to it.
Step-by-step explanation:
The electric potential inside a capacitor is related to the charge (Q) and voltage (V) on the capacitor. The energy stored in the capacitor is known as electrical potential energy. This energy is computed based on the fact that the first charge placed on an uncharged capacitor has no voltage change (ΔV = 0), and the last charge placed sees the full voltage (V), with the average voltage experienced by the charge being V/2. Therefore, the energy stored (Ecap) in a capacitor can be calculated using the formula:
Ecap = 1/2 QV
Additionally, the potential difference across a capacitor can be considered as an electromotive force (emf) only when the current is zero. Internal resistance of the capacitor causes the output voltage to differ from an emf when current is flowing. The electric field within a biological cell membrane, which can be modeled as a nano-sized capacitor, is another example demonstrating the concept of electric potential in capacitors. The cell membrane achieves an extremely high electric field strength that could theoretically create an electrical spark in air.