• A capacitor is a device that stores electric charge and potential energy. The capacitance C of a capacitor is the ratio of the charge stored on the capacitor plates to the the potential difference between them: (parallel) This is equal to the amount of energy stored in the capacitor. The E surface. 0 is the electric field without dielectric.
A capacitor is a device which stores electric charge. Capacitors vary in shape and size, but the basic configuration is two conductors carrying equal but opposite charges (Figure 5.1.1). Capacitors have many important applications in electronics.
Most capacitors contain at least two electrical conductors, often in the form of metallic plates or surfaces separated by a dielectric medium. A conductor may be a foil, thin film, sintered bead of metal, or an electrolyte. The nonconducting dielectric acts to increase the capacitor's charge capacity.
When a voltage V is applied to the capacitor, it stores a charge Q, as shown. We can see how its capacitance may depend on A and d by considering characteristics of the Coulomb force. We know that force between the charges increases with charge values and decreases with the distance between them.
An electric field forms across the capacitor. Over time, the positive plate (plate I) accumulates a positive charge from the battery, and the negative plate (plate II) accumulates a negative charge. Eventually, the capacitor holds the maximum charge it can, based on its capacitance and the applied voltage.
The simplest example of a capacitor consists of two conducting plates of area A , which are parallel to each other, and separated by a distance d, as shown in Figure 5.1.2. Experiments show that the amount of charge Q stored in a capacitor is linearly proportional to ∆ V , the electric potential difference between the plates. Thus, we may write
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Practical capacitors are available commercially in many different forms. The type of internal dielectric, the structure of the plates and the device packaging all strongly affect the characteristics of the capacitor, and its applications. Values available range from very low (picofarad range; while arbitrarily low values are in principle possible, stray (parasitic) capacitance in any circuit is t…