Capacitors and Capacitance: A capacitor is a two-terminal electrical component that stores electric energy in an electric field. It is made up of two conductive plates separated by a non-conductive material called a dielectric. The conductive plates store electric charges of equal and opposite sign, creating an electric field within the dielectric. The electric field stores energy, and the ability of a capacitor to store energy is called capacitance.

Capacitance is a measure of the amount of electric charge that can be stored on the conductive plates for a given potential difference (voltage) across the capacitor. The unit of capacitance is the farad (F), which is defined as the ability of a capacitor to store one coulomb of electric charge with a potential difference of one volt across its terminals. Capacitors are used in a wide range of applications, including power supply filtering, energy storage, signal coupling and decoupling, and voltage regulation. They play a critical role in many electrical and electronic systems and are an essential component of many devices.

The capacitance of a capacitor can be calculated using the formula C = εA/d, where C is the capacitance, ε is the dielectric constant of the material, A is the area of the conductive plates, and d is the distance between the plates. The capacitance of a capacitor can be increased by increasing the area of the conductive plates, decreasing the distance between the plates, or using a material with a higher dielectric constant.

Characteristics of Capacitors and Capacitance

The following are the main characteristics of Capacitors and Capacitance:

• Electric storage: Capacitors store electrical energy in an electric field.
• Two conductive plates: A capacitor consists of two conductive plates separated by a non-conductive material called a dielectric.
• Unit of capacitance: The unit of capacitance is the farad (F), which is the amount of electric charge that can be stored on the conductive plates with a potential difference of one volt across the capacitor.
• Capacitance formula: The capacitance of a capacitor can be calculated using the formula C = εA/d, where C is the capacitance, ε is the dielectric constant of the material, A is the area of the conductive plates, and d is the distance between the plates.
• Energy storage: The electric field within a capacitor stores energy, and the amount of energy stored is proportional to the square of the electric field.
• Voltage-dependent: The capacitance of a capacitor is proportional to the voltage across its terminals.
• Applications: Capacitors are used in a wide range of applications, including power supply filtering, energy storage, signal coupling and decoupling, and voltage regulation.
• Series and parallel connections: Capacitors can be connected in series or parallel to achieve different values of capacitance.
• Polarization: The electric field within a capacitor can induce polarization in the dielectric, which can affect the capacitance of the capacitor.

• Leakage current: Capacitors can exhibit a small amount of leakage current due to imperfections in the dielectric material.

Functions of Capacitors and Capacitance

Capacitors and Capacitance play a crucial role in many electrical and electronic systems and have several important functions, including:

• Energy storage: Capacitors can store electrical energy and provide it as needed, making them useful in applications such as power supplies and energy storage systems.
• Power supply filtering: Capacitors are commonly used in power supplies to filter out unwanted voltage fluctuations and noise, ensuring stable and clean power for the connected devices.
• Signal coupling and decoupling: Capacitors can be used to couple and decouple signals in electronic circuits, such as amplifiers and radio receivers.
• Voltage regulation: Capacitors can be used in voltage regulation circuits to maintain a constant voltage level despite changes in the input voltage.
• AC/DC conversion: Capacitors can be used to store energy from an AC voltage source and then release it as a DC voltage, making them useful in AC/DC power conversion applications.
• Noise suppression: Capacitors can be used to suppress high-frequency noise in electronic circuits.
• Resonance circuits: Capacitors are commonly used in resonance circuits, where they are used to tune the resonant frequency of the circuit.

• Timing circuits: Capacitors can be used in timing circuits, such as oscillators, to control the time constant of the circuit.

Formulas of Capacitors and Capacitance

Formulas of Capacitors and Capacitance are:

Charge on Capacitor

Note: Charge on the capacitor is Q.

Total charge/ the net charge on the capacitor is –Q + Q = 0.

Capacitance

The charge on the capacitor (Q) is directly proportional to the potential difference (V) between the plates i.e.

or Q = CV

The constant of proportionality (C) is termed as the capacitance of the capacitor.

Dimensional Formula and Unit of Capacitance

• Unit of Capacitance: Farad (F)

The capacitor value can vary from a fraction of pico-farad to more than a micro Farad. Voltage level can range from a couple to a substantial couple of hundred thousand volts.

• Dimensional Formula: M^-1L^-2I²T⁴

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By Team Learning Mantras