 A capacitor consists of two plates separated by an insulating material called the dielectric. Capacitors store energy in the form of an electrostatic charge. Capacitors are assigned a numerical value called the ferrid. The number corresponds to the amount of charge the capacitor can store. The greater the ferrid value, the larger the charge it can store. Even though the ferrid is the basic unit of capacitance, it is seldom used because it's an extremely large amount of capacitance. A more common unit of measurement for capacitors is the microferrid, which is abbreviated the following ways. These abbreviations are listed on schematic diagrams and are printed on the case of the capacitor. Capacitor values are also commonly expressed in picofarads. That unit is abbreviated in the following ways. The value of a capacitor is determined by the following three factors. Area of the plates, distance between the plates, dielectric constant, which is based on the material that the dielectric is made of. The value of the capacitor can be calculated by the following formula. C equals K times A over 4.45 times D, where C equals the capacitance in picofarads, K equals the dielectric constant, A equals the area of one plate, D equals the distance between the plates, and 4.45 equals the numerical constant. If the plate area increases, the capacitance increases proportionally. Between the plate area doubles the capacitance value. If the distance between the plates increases, there is an inversely proportional decrease of the capacitance. The dielectric constant number for capacitance uses air as a reference. Air has a numerical dielectric constant of one. By using a material other than air for a dielectric, such as mylar, which has a dielectric constant of 3.0, the capacitance value in farads will increase by 3. This means the capacitor using mylar will store a charge three times greater than the charge stored by an air capacitor with the same physical dimensions. The following table shows the dielectric constant of various materials. You have completed this activity, capacitor values.