Capacitor

Overview

A capacitor is a passive electronic component designed to store and release electrical energy in an electrostatic field. Unlike a battery, which stores energy chemically and releases it slowly, a capacitor stores charge physically and can discharge it almost instantaneously.

Core Construction & Operation

A 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 across the dielectric, causing positive charge to accumulate on one plate and negative charge on the other. The amount of charge a capacitor can store is determined by its capacitance, which depends on the surface area of the plates, the distance between them, and the properties of the dielectric material.

1. Charging: When a voltage is applied across the leads, an electric field develops across the dielectric. Positive charge accumulates on one plate and negative charge on the other.
2. Holding Charge: The dielectric prevents direct electrical current from flowing between the plates, maintaining the separated charges and holding the energy.
3. Discharging: When the circuit provides a path between the plates, the stored charge flows out rapidly to equalize the potential.

Key Electrical Metrics

• Capacitance (C): Measured in farads (F), it indicates how much charge a capacitor can store per volt of applied voltage.
• Voltage Rating: The maximum voltage the capacitor can safely handle without breaking down.
• Equivalent Series Resistance (ESR): Represents the internal resistance that causes energy loss during charging and discharging.
• Leakage Current: The small amount of current that leaks through the dielectric over time, even when the capacitor is not connected to a circuit.