Capacitance

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Plate CapacitorII

Cylindrical CapacitorII

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Eccentric capacitor

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Parallel Wire Capacitance

Spherical Capacitor

Capacitance is a fundamental electrical property of a capacitor that quantifies how much electric charge can be stored in an object for a given electric potential difference across it. The unit of capacitance is the farad (F), named after the English physicist Michael Faraday. One farad is defined as the capacity to store one coulomb of charge with a potential difference of one volt.

Overview

Capacitance is determined by the physical characteristics of the object, including its size, shape, and the dielectric material between the conductors. In its simplest form, a capacitor consists of two conductors separated by a non-conductive region. The non-conductive region can be a vacuum, air, or any other material, which acts as the dielectric. The formula for the capacitance C of a parallel-plate capacitor is given by:

C = \frac{\epsilon A}{d}

where C is the capacitance, \epsilon is the permittivity of the dielectric material, A is the area of one of the plates, and d is the distance between the plates.

Applications

Capacitance has critical applications in various electronic and electrical engineering fields. It is used in the design of circuits, such as filters, oscillators, and power supply circuits. Capacitors are also essential components in digital electronics, where they are used for timing and waveform shaping.

Types of Capacitors

There are many types of capacitors, designed to cater to specific needs and applications. These include:

• Ceramic capacitors: Made of ceramic material as the dielectric. They are commonly used for high-frequency applications.
• Electrolytic capacitors: Known for their high capacitance values, making them suitable for power supply filtering applications.
• Tantalum capacitors: Similar to electrolytic capacitors but with better performance and reliability, used in space-sensitive applications.
• Film capacitors: Made with plastic film as the dielectric, used for high-frequency applications and in situations requiring stable capacitance.

Factors Affecting Capacitance

Several factors can affect the capacitance of a capacitor, including:

• Dielectric Material: The type of material between the plates significantly influences the capacitance. Different materials have different permittivity values.
• Geometry: The shape and size of the capacitor affect its capacitance. Larger plate areas and shorter distances between plates increase capacitance.
• Temperature: Capacitance can vary with temperature due to changes in the dielectric material's properties.

Capacitance in Series and Parallel

When capacitors are connected in series or parallel, their total capacitance changes.

• In series, the total capacitance is less than any individual capacitor's capacitance.
• In parallel, the total capacitance is the sum of all capacitors' capacitances.

See Also

• Electric field
• Dielectric
• Inductance
• Resistor