Module 3: Capacitance Basics

A capacitor is an electrical component that stores energy in an electric field. It consists of two conductive plates separated by a non-conductive material called a dielectric.

Capacitance (measured in Farads) is the ability of a capacitor to store an electrical charge. It depends on factors like the area of the plates, distance between them, and the type of dielectric material used.

The area of the plates directly affects capacitance. A larger plate area allows for more charge to be stored, leading to higher capacitance.

The distance between the plates is inversely proportional to capacitance. A smaller distance between plates results in higher capacitance.

The type of dielectric material between the plates influences capacitance. A dielectric with a higher dielectric constant will increase the capacitance.

A type of capacitor whose capacitance can be adjusted by changing the overlapping area of its plates.

A small variable capacitor used for precise adjustments, often in circuits.

The time it takes for a capacitor to charge to a certain percentage of its maximum voltage in a circuit.

The relationship between voltage and current in a circuit containing a resistor and capacitor.

The process of charging a capacitor in a circuit. Voltage across the capacitor increases exponentially with time.

The ability of a capacitor to store electrical energy.

Unit of capacitance, often abbreviated as 'pF'.

A measure of how much a capacitor's value can vary from its nominal value.

Increasing the surface area of the capacitor plates allows for a larger amount of charge to be stored. This is because a larger area provides more space for charge accumulation.

When a voltage is applied to a capacitor, electrons move from one plate to the other, creating an electric field between the plates. This movement of electrons is what constitutes the 'charging' of the capacitor.

A dielectric is a non-conductive material that separates the plates of a capacitor. It helps to increase the capacitance by reducing the electric field strength between the plates.

When a capacitor is connected to a DC voltage source, it will charge until the voltage across its plates equals the applied voltage. Then, the capacitor blocks further DC current flow.

When an AC voltage is applied to a capacitor, it will charge and discharge continuously, following the changing voltage. This results in an alternating current flowing to and from the capacitor.

Even though current flows in the wires connected to a capacitor under AC, no electrons actually travel across the dielectric between the plates. Instead, the electric field changes, creating the illusion of current flow.

A capacitor is an electronic component that stores electrical energy in an electric field. It consists of two conductive plates separated by an insulating material called a dielectric.

The capacitance decreases as the distance between the plates increases. A greater separation reduces the strength of the electric field, leading to less stored charge.

Adding more plates increases the total surface area available for charge storage. However, it also affects the effective distance between the plates.

The dielectric material between the capacitor plates influences capacitance. A material with a higher dielectric constant (k) allows for more charge storage.

The voltage rating specifies the maximum voltage that can be applied across a capacitor before it breaks down. Exceeding this rating can damage the capacitor permanently.

Capacitors can be connected in series or parallel, affecting their overall capacitance. In a series connection, capacitances add reciprocally, while in parallel, capacitances add directly.

Capacitors do not charge or discharge instantaneously. They exhibit an exponential charge and discharge behavior characterized by a time constant (τ). This constant represents the time it takes for the capacitor to charge or discharge to approximately 63.2% of its final value.

The time it takes for the voltage across a capacitor to reach 63.2% of the source voltage in an RC circuit.

The formula used to calculate the time constant in an RC circuit. TC is directly proportional to both resistance and capacitance.

The process of a charged capacitor gradually releasing its stored energy through a resistor in an RC circuit.

The amount of time it takes for a capacitor to discharge to about 36.8% of its initial voltage (1-63.2%) in an RC circuit.

In an RC circuit, after 5 time constants have passed, the capacitor will be considered fully discharged and the voltage across it will be effectively zero.

The time it takes for the voltage across a capacitor to reach its full potential, equal to the source voltage.

The time it takes for the voltage across a capacitor to reach 63.2% of the source voltage in an RC circuit, regardless if it is charging or discharging.

The time constant (TC) of an RC circuit affects how quickly the capacitor charges and discharges, impacting the overall performance of the circuit.

A simple visual inspection method for checking the health of a capacitor. It involves looking for signs of physical damage, such as bulging or swelling. Bulging often indicates a capacitor is malfunctioning.

The process of ensuring a capacitor is completely discharged before handling. This is crucial for safety and to prevent damage to the capacitor or any measuring instruments.

A device used to measure capacitance, often measured in Farads (F). It allows testing the storage capacity of a capacitor.

A method used to determine the capacitance value of a capacitor. This involves utilizing a circuit with a resistor and a power supply, and measuring the time it takes the capacitor to charge to a specific voltage level. The time constant (TC) is calculated as RC, where R is resistance and C is capacitance.

A method used to test a capacitor's health using an analogue ohmmeter. This involves setting the ohmmeter to its highest resistance range and connecting it across the capacitor's terminals. A good capacitor will show an initial low resistance that gradually increases, signifying its charging behavior.

A condition in a capacitor where it no longer functions and offers a very low resistance even without any charge. This results in an immediate discharge, indicating failure.

To test the functionality of a capacitor, it is typically disconnected from the circuit. This helps prevent any interference from the circuit's components and ensures accurate readings.