This is one of those age-old questions that has probably been one that has bothered lots of people! We were probably all taught exactly what a capacitor does and is back at school, but it is one of those pieces of information that seemed useless to us at the time and probably deleted itself from the memory bank! However, as an adult there are numerous situations where it would have been quite useful to have retained that knowledge. From staff in electrical stores talking about capacitors in televisions, to engineers telling us about the capacitor in a digital camera, it would be useful to know what they are talking about.
The capacitor was first invented using the Leyden Jar by a Dutch Professor. Using a jar, water and foil he created the dielectric and plates which would hold equal but opposite charges. It was then Michael Faraday who took this concept and used it practically to store unused energy in his various experiments. From there the first ever usable capacitor was created, and Faraday is now given the credit of helping us to deliver electric power over great distances. So that is how the capacitor came to be, but what does it actually do and how does it work?
Very simply, a capacitor is an electrical component that stores electrical charge. It works by separating two conductors with an insulator in between, that is how you make a capacitor. Normally the two conductors are called plates and the insulator is called the dielectric. The capacitor then stores the electrical energy for when it is needed. A capacitor discharges by having a voltage applied over the two plates, which creates an electric field. Then this charge is stored on the plates, with the negative and positive charge separated from each other. You measure the energy in a capacitor or the measurement of capacitance, is called the farad. The larger this is the more energy the capacitor can store. When you add energy to it you are charging it, and when that energy is released, that is called discharging. A capacitor will discharge really quickly, in order to perform certain functions.
These could include smoothing the output of various power supplies, so perhaps by supplying a second of power when the socket outlet may unexpectedly drop power for example. They are also used in circuits to block direct current and allow alternating current to go through. They also often stabilize voltage and power flow in various circuits. A capacitor will basically be found in nearly every electronic device ever made, from huge machines (like your air conditioner) to your small iphone, there will be one in there! You will find them in many places because quite simply, they can do many things. They can take on noise reduction, power storage as well as filtering options. The humble capacitor is one of those brilliant inventions that is all around us and we often have no idea!