Capacitance

Key Stage 5

Meaning

Capacitance is the ability of a system to store an electric charge per unit of potential difference (pd), measured in farads (F).

About Capacitance

• The unit of capacitance is the farad (F), which is equal to one coulomb per volt.
• Factors affecting capacitance include the area of the plates, the distance between them, and the dielectric material between the plates.
• Capacitors in series have a reduced total capacitance, while those in parallel have an increased total capacitance.
• Capacitance is a measure of a capacitor's ability to store charge.
• In DC circuits, a capacitor charges and discharges, storing and releasing energy.
• In AC circuits, capacitors block direct current and allow alternating current to pass, acting as a reactive component.

Formula

The capacitance 𝐶 of a capacitor is given by:

𝐶=𝑄𝑉

Where:

𝐶 is the capacitance of the capacitor

𝑄 is the charge stored in the capacitor

and

𝑉 is the potential difference across the capacitor.

Examples

• A parallel-plate capacitor consists of two conductive plates separated by an insulating material.
• Used in electronic circuits to store energy, filter signals, and in timing applications.