How do capacitors work?

Answer 1

A capacitor stores electrical energy.
They cant hold any where near the amount that a battery can though, for the same size.

It is formed by any two conductors that are seperated by a gap, or insulator. The two conductors are usually thin sheets of metal, and an insulator is placed between them.
The closer together the two plates, and the greater the surface area will increase the ability of the device to store energy.
The energy stored in Joules is = 0.5 * C * V * V.

The capacitors energy is stored in the insulator, which is usually called the dielectric. Most capacitors use some type of thin plastic film which separates the metal plates.
When voltage is applied across the two plates, the orbits of the electrons in the plastic insulator experience a force which causes the orbits to stretch like a rubber band.
Electrons have a negative charge, and like charges repel each other. Plus attracts minus, but minus repels minus, and plus repels plus. So the electron orbits in the insulator are streched towards the plus plate, and repelled by the negative plate.
This stretching requires work to be performed. If you used a battery to charge up the capacitor, then remove the battery, the orbits of the insulator are still streched, even though you broke the circuit. Actually, you can dis-assemble the capacitor by removing the insulator, and touching the two plates of metal together, and no spark will be seen. But if you reassemble the capacitor and touch the plates, then you will see a spark.
This is because the energy is stored in the dielectric.
In the disassembled capacitor, the insulator will have a charge on its surface, just like a piece of styrofoam with a good static charge.

Try the experiment with two metal buckets, and a plastic bucket.
Assemble the buckets, and charge up the bucket capacitor.
Carefully remove the plastic bucket, and touch the two metal buckets together, no spark. Reassemble and note the capacitor is charged, touching the plates produces a spark.

There are thousands of different capacitors. Why is that.
Each one is specalized, but basically the same.
The insulator changes thickness and may change in lenght when the temperature is changed, or voltage is applied. This would change the value of the capacitor. This would not be a good choice if the capacitor is used in a radio receiver, where the value deturmines the frequency of an oscillator, or filter.
So the insulator is chosen carefully, so that it does not change shape over temperature. For stability over temperature, ceramic, Mica, polystyrene are some of the best. But their "dielectric constant" is not as high as other materials.
The higher the dielectric constant, the greater storage energy the capacitor will have, if all other factors are equal.

For large capacitors, usually two long strips of Aluminum foil are rolled up, which provides a lot of surface area. Old capacitors used an insulator between the plates, such as wax paper, or plastic. But modern Aluminium capacitors use a chemical paste that is initially conductive, but after application of current for a short peroid of time, causes an insulative material to form on one of the two metal foils, depending on the direction of the applied external voltage.
This is done at the factory, where they mark the capacitor, one end is marked with a negative sign. 'These are called electrolytic capacitors, and are cylindrical in shape.

The value of the capacitor is given by: C=e*A/D
Where C is the capicitance, e is permitivity of the dielectric, A is the area, and D is the distance between the two plates.
So you can see that making A area bigger will help, and if e is larger. D is on the bottem, so a lower number on the bottem ( smaller distance between the plates is better).

Where are capacitors used: Just about every where.
A photo flash capacitor in a flash camera has rolled up Aluminum foil, but it is very thick, and the insulator is very good.
The insulator can usually block 450V or so, and the capacitor value is about 330uF ( micro Farad)
Capacitor storage is measured in Farads.

Austin Semiconductor

Answer 2

A capacitor is a little like a battery. Although they work in completely different ways, capacitors and batteries both store electrical energy. If you have read How Batteries Work, then you know that a battery has two terminals. Inside the battery, chemical reactions produce electrons on one terminal and absorb electrons on the other terminal. A capacitor is much simpler than a battery, as it can't produce new electrons -- it only stores them.
In this article, we'll learn exactly what a capacitor is, what it does and how it's used in electronics. We'll also look at the history of the capacitor and how several people helped shape its progress.
Inside the capacitor, the terminals connect to two metal plates separated by a non-conducting substance, or dielectric. You can easily make a capacitor from two pieces of aluminum foil and a piece of paper. It won't be a particularly good capacitor in terms of its storage capacity, but it will work.
In theory, the dielectric can be any non-conductive substance. However, for practical applications, specific materials are used that best suit the capacitor's function. Mica, ceramic, cellulose, porcelain, Mylar, Teflon and even air are some of the non-conductive materials used. The dielectric dictates what kind of capacitor it is and for what it is best suited. Depending on the size and type of dielectric, some capacitors are better for high frequency uses, while some are better for high voltage applications. Capacitors can be manufactured to serve any purpose, from the smallest plastic capacitor in your calculator, to an ultra capacitor that can power a commuter bus. NASA uses glass capacitors to help wake up the space shuttle's circuitry and help deploy space probes. Here are some of the various types of capacitors and how they are used.
Air - Often used in radio tuning circuits
Mylar - Most commonly used for timer circuits like clocks, alarms and counters
Glass - Good for high voltage applications
Ceramic - Used for high frequency purposes like antennas, X-ray and MRI machines
Super capacitor - Powers electric and hybrid cars

https://www.electrikals.com/

Answer 3

actually a capacitor holds a value. So while the fan is became on the capacitor says cost the electrons. it is how the motor knows while to instruct on. the different human beings right here have studied greater electronics then I, and would have a greater helpful answer.

Answer 4

They are like a large battery. They charge up with house current. Then when a motor starts up it releases the charge to help get the motor started.

Answer 5

Here is a good explanation for you to check out...
http://www.satcure-focus.com/tutor/page6.htm
Good luck with it.