The capacitance of a capacitor is its ability to accumulate an electric charge. The formula for the electrical capacity is as follows.
This value is measured in farads. As a rule, the capacity of the element is very small and is measured in picofarads.
In problems it is often asked how the capacity of the capacitor will change if the charge or voltage is increased. This is a trick question. We draw another analogy.
Imagine that we are talking about an ordinary bank, not a condenser. For example, you have it three-liter. A similar question: what will happen to the capacity of the can, if it pours 4 liters of water? Of course, the water will simply pour out, but the size of the jar will not change.
The same is with capacitors. Charge and voltage does not affect the capacitance in any way. This parameter depends only on actual physical dimensions.
The formula is the following
Only these parameters affect the real capacitance of the capacitor.
On any capacitor there is a marking with technical parameters.
It is not difficult to understand. Enough minimal knowledge of electricity.
Condensers, as well as resistors, can be connected in series and in parallel. In addition, in the schemes there are also mixed compounds.
As you can see, the capacitance of the capacitor in both cases is treated differently. This also applies to voltage and charge. The formulas show that the capacitance of the capacitor, or rather of their aggregate in the circuit, will be the largest with parallel connection. In the case of a serial, the total capacity is significantly reduced.
When connected in series, the charge is placed evenly. It will be the same everywhere - both total and on each capacitor. And when the connection is parallel, the total charge is added. This is important to remember when solving problems.
Voltage is considered vice versa. With a serial connection we add up, and when parallel, it is equal everywhere.
Here you have to choose: if you need more tension, then we sacrifice capacity. If the capacity, then there will not be a huge voltage.
Types of capacitors
There is a huge number of capacitors. They differ in both size and shape.
Of course, the capacity is calculated in all different ways.
The capacitance of a plane capacitor
The electrical capacitance of a flat capacitor is most easily determined. This formula basically everyone and remember, unlike others.
Here everything depends on the physical parameters and the medium between the plates.
It is also of great importance here which dielectric or material is placed inside. Since the part has the size of a sphere, its capacity depends on the radius.
In the case of a cylindrical shape, except for the medium inside, the values have radii and the length of the cylinder.
Damage in capacitors
Think about how the electrical capacitance of a flat capacitor will change if it is damaged? There are various malfunctions that can affect the performance of capacitors.
For example, they crumble or swell. After that they become unsuitable for the normal operation of the device where they are installed.
Consider examples of damage and failure of capacitors. All can swell at once.
Sometimes only a few out of order. This happens when capacitors of different parameters or qualities.
A clear example of spoilage (swelling, rupture and outflow of contents).
If you see these tapes, this is the extreme degree of damage. Worse and can not be.
If you notice such swollen condensers on the device (for example, on a video card in a computer), this is an occasion to think about replacing the part.
Similar problems can be eliminated only by replacing them with a similar part. You must match all the parameters one by one. Otherwise, the work may be incorrect or very short-lived.
Change the capacitors carefully, without damaging the board. It is necessary to solder quickly, avoiding overheating. If you do not know how to do this, it's best to take the part for repair.
The main cause of failure is overheating, which occurs in the case of aging or large resistance in the circuit.
It is recommended not to tighten with repair. Since the capacity of the damaged capacitors changes, the device where they are located will operate with a deviation from the norm. And in time this can cause a breakdown.
If you have a video card that has swollen capacitors, their timely replacement can correct the situation. Otherwise, you can burn chip or something else. In this case, the repair will be very expensive or even impossible.
Above was an example with a jar of water. It said that if you pour more water, then the water will flow out. And now think, where can the electrons "pour out" into the condenser? After all, it is sealed completely!
If you feed more current into the circuit than the one to which the capacitor is designed, then as soon as it is charged, its excess will try to go out somewhere. And there is no free space. The result will be an explosion. In the case of a slight excess of charge, cotton will be small. But if you give a colossal amount of electrons to the capacitor, it will simply rupture, and the dielectric will flow out.