A capacitor or stack is two parallel metal plates with a layer of air or insulation between them. They store electrical energy and are used in resistor circuits along with resistors. Capacitors are also used to smooth the surface of direct voltage changes. From Are also used in circuits as filters. Because capacitors easily pass intermittent signals but prevent direct signals from passing.
A capacitor is an electrical element that can store electrical energy through an electrostatic field (electric charge). Capacitors are used in electrical circuits. The capacitor is represented by the letter C, which is the beginning of the word capacitor.
Due to the fact that the electric charge is stored in the capacitor; Capacitors can be used to create uniform electric fields. Capacitors can hold electric fields in small volumes; In addition, they can be used to store energy.
Capacity is a measure of the ability to store electrical energy. High capacitance means that the capacitor is able to store more electrical energy. The unit of measurement is Farad capacity. 1 Farad is a large unit and indicates high capacity. Therefore, the use of smaller units is also common in capacitors. Microfarad µF, nanofarad nF and picofarad pF are the smaller units of Farad.
µ means 10-6 (millionth), so 1000000µF = 1F
n means 10-9 (thousand-millionth), so 1000nF = 1µF
p means 10-12 (million-millionth), so 1000pF = 1nF
Types of capacitors
A. Electrolyte capacitors
In electrolyte capacitors, positive and negative poles are marked on their bodies and are used in circuits based on poles. There are two types of designs for the shape of these capacitors. One is the axial shape, in this type of bases, one is on the right side and the other is on the left side, and the other is radial, in which both capacitor bases are on one side. An example of an axial and radial capacitor is shown.
In electrolyte capacitors, their capacitance is written as a number on their body. The tolerance voltage of the capacitors is also written on their body and this voltage should be considered when choosing a capacitor. These capacitors are not damaged unless they are heated hot.
B. Tantalum capacitors
Tantalum capacitors are also polarized and, like electrolyte capacitors, usually have a low voltage. These capacitors are usually available in small and expensive sizes and therefore offer a high capacity in small size.
In the new Tantalum capacitors, voltage and capacitance are written on their body, but in the old types, a colored bar is used, for example, it has two lines (for two digits) and there is a colored dot for the number of zeros, which has the capacity per microfarad. They specify. For the first two digits, color standard codes are used, but for the number of zeros and the color location, gray means × 0.01 and white means × 0.1. The third colored bar near the end indicates the voltage so that if this line is yellow it shows 6.3 volts, policy 10 volts, green 16 volts, blue 20 volts, gray 25 volts and white 30 volts.
For example, blue-gray colors and black dots mean 68 microfarads.
Blue-gray and white dot mean 6.8 microfarads.
The internal structure of the capacitor consists of two main parts: conductor plates and insulation
Insulation between conductors (dielectric)
Whenever two conductors are placed opposite each other and insulation is placed between them, they form a capacitor. Capacitor conductor plates are usually made of aluminum, zinc and silver with relatively high surface area, and among them (dielectric) insulation (air, paper, mica, plastic, ceramic, aluminum oxide and tantalum oxide) are used. The larger the dielectric coefficient of an insulating material, the better its insulating properties. For example, the dielectric coefficient of air is 1 and the dielectric coefficient of aluminum oxide is 7. Therefore, the insulating property of aluminum oxide is 7 times the insulating property of air.
Application of capacitors in digital and analog circuits
In digital circuits, capacitors are used as an energy storage element that is charged at one moment and de-charged at another, but in analog circuits, capacitors are used to isolate (separate) two alternating and direct sources. The capacitor acts as a short circuit against alternating voltage and allows entry or exit, but against direct voltage it acts as a barrier and does not allow direct voltage to enter or leave the circuit to its isolated part.
Charging or charging a capacitor
When connecting a chargeless capacitor to both ends of a battery; Electrons are current in the circuit. In this way, one page gets a positive charge and the other page gets a negative charge. The plate connected to the positive terminal of the battery; The load is positive and the other page is negative. The capacitor is charged after storing a certain amount of electric charge. This means that the switch is still closed, but no current passes through the circuit, and in fact the current reaches zero. That is, as soon as we connect an empty capacitor without load in a circuit to the generator; After a short time, the galvanometer hand returns to zero. That is, no current flows through the circuit. In this case we say the capacitor is full.
Discharge or discharge a capacitor
First we consider the capacitor that is full. Connect the two ends of the capacitor with a wire. In this case, a current is established in the circuit for a short time and this current is maintained as long as there is a load on the capacitor plates. After a while the current will be zero. This means that there is no more charge on the capacitor plates and the capacitor is discharged.
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