The role and principle of capacitance that you don't know

A capacitor is a component that stores charge, and its main function is to store electrical energy. It can play a role in filtering, DC blocking, and denoising in the circuit, and is widely used in electric power, electronics, communication and other fields.

This article will introduce the function and principle of capacitors in detail from the basic concept, working principle, classification and application of capacitors.

1. The basic concept of a capacitor. A capacitor is separated by two conductor plates and insulated. The two conductor plates are respectively connected to both ends of the power supply. The air gap in the middle is called the dielectric of the capacitor. When the capacitor is connected to the power supply, the air gap between the conductor plates is filled with electrons, thereby forming an electric field, and the capacitor stores the charge. The energy storage capacity of a capacitor is related to its capacitance. Capacitance is usually expressed in C, the unit is Farad (F), and 1 Farad is equal to 1 Coulomb/Volt. The formula is C=Q/V, where Q is the amount of charge stored in the capacitor and V is the voltage of the capacitor.

2. The working principle of the capacitor When the electric field strength increases, the charge storage capacity also increases correspondingly, and the quantity representing the electric field strength is the electric field strength E of the capacitor. The smaller the distance between the conductor plates, the greater the electric field strength. When the capacitor is powered on, the charge from the power supply flows into the capacitor, and at the same time, an electric field is formed between the conductor plates, and the strength of the electric field is also increasing until it reaches the limit value of the capacitor, and no new charge will enter the capacitor. When the capacitor charge is saturated, the electric field strength formed between the conductor plates reaches the maximum value, and the capacitor can store energy at this time. After the electric charge stored in the capacitor reaches the maximum value, the power supply is disconnected from the capacitor, but the electric charge stored before can be kept forever. When the power source is reconnected to the capacitor, the stored charge begins to be released.

3. Classification of capacitors Capacitors are divided into solid capacitors, liquid capacitors and gas capacitors according to the nature of the dielectric. Among them, solid capacitors are divided into ceramic capacitors, plastic capacitors, ferroelectric capacitors, etc. Each capacitor has its own advantages and disadvantages, and the scope of use is also different. Liquid capacitors use liquid (such as sulfuric acid) as a dielectric, and they are usually composed of electrolytic capacitors, oscillation capacitors, etc. Gas capacitors use gas (such as helium, nitrogen, etc.) as dielectrics. They are usually used in radio frequency circuits and can meet the requirements of high-frequency operation. They are composed of transformer capacitors and spiral capacitors.

4. Application of capacitors

1. As a filter capacitor One of the most common applications of capacitors is as a filter capacitor in electronic circuits to remove high-frequency components in AC signals and leave DC components in AC signals.

2. Used as DC blocking capacitor Capacitors can also be used as DC blocking capacitors in DC circuits to isolate AC and DC, thereby ensuring the stability of DC signals.

At the same time, it can also protect downstream circuits.

3. Smoothing capacitors for power supply Capacitors can also be used for smoothing capacitors for power supplies to eliminate noise and changes in the power supply and ensure the normal operation of the circuit. This usage is very common in electrical equipment such as entertainment equipment, televisions, and computers.

4. Capacitors used in oscillating circuits can generate sine waves by using oscillating circuits. Analog circuits such as sound and images all require oscillating circuits, and in oscillating circuits, capacitors often play an important role.

5. Used in sensors Capacitive sensors use the properties of capacitors to measure the capacitance change of the measured object to realize the measurement of the measured object, such as temperature, humidity, water level, etc. To sum up, the function and principle of capacitors are closely related to our lives. Capacitors play an important role in electronic equipment, communication systems, power systems and other fields. Continuous development, innovation, and continuous updating have become essential to our daily life. components.