Capacitance

Storing Charge: Understanding Capacitance

Capacitance is the ability of a system of conductors and insulators to store electric charge. It is a measure of how much electric charge is stored for a given electric potential (voltage). A component with high capacitance can store a large amount of charge at a low voltage, while a low-capacitance component would require a much higher voltage to store the same amount of charge. The physical device designed to have a specific capacitance is called a capacitor, a fundamental passive component in virtually all electronic circuits.

A simple capacitor consists of two conductive plates separated by an insulating material called a dielectric. When a voltage is applied across the plates, an electric field develops in the dielectric, causing positive charge to collect on one plate and negative charge on the other. This stored charge can then be released when needed. The SI unit of capacitance is the Farad (F), named after the English physicist Michael Faraday. Capacitors are used for a huge variety of tasks in electronics, including energy storage (like in a camera flash), filtering out noise from power supplies, blocking DC current while allowing AC current to pass, and creating timing circuits. This converter helps you navigate the vast range of capacitance values, from the very large Farad to the tiny Picofarad, used for different electronic applications.

Relevant Formulas in Science and Mathematics

• Definition of Capacitance (Physics): The fundamental relationship is C = Q / V, where 'C' is capacitance, 'Q' is the magnitude of the charge stored on each plate, and 'V' is the voltage across the capacitor.
• Energy Stored in a Capacitor (Physics): The potential energy (U) stored in a capacitor is given by U = ½ * C * V².
• Capacitance of a Parallel-Plate Capacitor (Physics): The capacitance of a simple parallel-plate capacitor can be calculated as C = (k * ε₀ * A) / d, where 'k' is the dielectric constant of the insulator, 'ε₀' is the permittivity of free space, 'A' is the area of the plates, and 'd' is the distance between them.
• Capacitors in Parallel (Physics): When capacitors are connected in parallel, their total capacitance is the sum of their individual capacitances: C_total = C₁ + C₂ + C₃ + ....
• Capacitors in Series (Physics): When capacitors are connected in series, the reciprocal of the total capacitance is the sum of the reciprocals of the individual capacitances: 1/C_total = 1/C₁ + 1/C₂ + 1/C₃ + ....

A Deep Dive into Common Capacitance Units

• Farad (F): The SI unit of capacitance. A capacitor has a capacitance of one Farad if a charge of one Coulomb on its plates results in a potential difference of one Volt. The Farad is an extremely large unit of capacitance. In practice, most capacitors used in electronics have values that are many orders of magnitude smaller.
• Microfarad (µF): Equal to one-millionth of a Farad (1 F = 10⁶ µF). This is one of the most common units for electrolytic and film capacitors used in power supplies and audio circuits.
• Nanofarad (nF): Equal to one-billionth of a Farad (1 µF = 1000 nF). This unit is common for smaller ceramic and film capacitors used in filtering and coupling applications in digital and analog circuits.
• Picofarad (pF): Equal to one-trillionth of a Farad (1 nF = 1000 pF). This is a very small unit of capacitance, used for tiny ceramic or silver mica capacitors in high-frequency circuits, such as radio circuits, and to describe the stray capacitance that unintentionally exists between components.