Since the beginning of the study of electricity to solve the question of its accumulation and preservation was only in 1745 Ewald Jurgen von Kleist and Pieter van Musschenbroek.Founded in the Dutch Leiden device allowed to accumulate electrical energy and use it when needed.
Leyden jar - a prototype capacitor.Its use in physical experiments promoted the study of electricity far in advance has created a prototype of an electric current.
What capacitor
collect the electric charge and electricity - the main purpose of the capacitor.Typically, a system of two insulated conductors arranged as close as possible to each other.The space between conductors is filled with a dielectric.Charge accumulates on the conductors is selected heteronymic.The property is opposite charges attract promotes greater its accumulation.Dielectrics assigned dual role: the higher the dielectric constant, the greater the electrical capacitance, charges can not overcome the barrier and neutralized.
Electric capacity - the main physical quantity characterizing the possibility of the capacitor to store charge.Guides plates called electric field focuses capacitor therebetween.
Energy charged capacitor, appear to be dependent on its capacity.
Electric capacity
energy potential makes it possible to apply (a large electrical capacitance) of the capacitor.Energy charged capacitor is used, if necessary, apply a short-current pulse.
From what depends on electrical capacitance values?The charging process starts with the capacitor electrodes connecting it to the poles of the current source.Accumulate on one plate charge (the value of which q) is taken as the charge on the capacitor.The electric field is concentrated between the electrodes has a potential difference U.
Electric capacity (G) depends on the quantity of electricity that is concentrated on one conductor and the field voltage: C = q / U.
this value is measured in F (farads).
capacity of the entire Earth can not be compared to the capacity of the capacitor, the magnitude of which around a notebook.Accumulated powerful charge can be used in the art.However
accumulate unlimited amounts of electricity on the plates is not possible.When the voltage increases to a maximum value of capacitor breakdown may occur.Plates are neutralized, which can lead to damage of the device.Energy charged capacitor is thus completely in his heat.
The energy
Heating capacitor is due to the conversion of the energy of the electric field in the interior.The ability of the capacitor to perform the work on the movement of the charge indicates the presence of an adequate supply of electricity.To determine how great the power of a charged capacitor, consider the process of detente.Under the influence of an electric field voltage U charge q flows from one plate to another.By definition, the work of the field is equal to the potential difference in the amount of charge: A = qU.This relation is valid only for constant voltage, but in the process of detente on the plates of the capacitor gradually decrease to zero it.To avoid inaccuracies, we take the average value U / 2.
electric capacity from the formula, we have: q = CU.
Hence the energy of a charged capacitor can be determined by the formula:
W = CU2 / 2.
see that its value is greater, the higher the electrical capacitance and voltage.To answer the question of what is the energy of a charged capacitor, turn to their species.
Types of capacitors
Since the energy of the electric field that is concentrated inside the condenser is directly related to its capacity and operation of the capacitors depends on their design features, use different types of drives.
- The shape of the plates: flat, cylindrical, spherical, and so on. D.
- By capacity Change: constant (the capacity is not changed), variables (changing the physical properties change capacity), Trimmers.Capacitance change may be carried out by changing the temperature, mechanical or electrical voltage.Electrical capacitance of the tuning capacitor is changed by changing the area electrodes.
- By type insulator: gas, liquid, solid dielectric.
- By type insulator: glass, paper, mica, metallized, ceramic, thin-films of various compositions.
Depending on the type of distinction and other capacitors.Energy charged capacitor depends on the dielectric properties.The main value is called the dielectric constant.Electrical capacitance is directly proportional to it.
flat capacitor
Consider a simple device to collect electric charge - plate capacitor.This is a physical system consisting of two parallel plates between which the dielectric layer.
plate shape may be rectangular, and circular.If you need to receive a variable capacity, it decided to take the plates in the form of half-disks.Turn one plate relative to the other causes a change in the area of the plates.
We assume that the area of one plate is S, the distance between the plates take equal d, the dielectric constant of the filler - ε.Electric capacity of the system depends only on the geometry of the capacitor.
C = εε0S / d.
Energy plane capacitor
see that the capacitance is directly proportional to the total area of one plate and inversely proportional to the distance between them.The proportionality factor - the electric constant ε0.The increase in the permittivity of the dielectric allow to increase electric capacity.Reducing the area of the plates provides a trimmer capacitor.The energy of the electric field of a charged capacitor depends on its geometrical parameters.
use the calculation formula: W = CU2 / 2.
Determining Energy charged capacitor planar shape is carried out according to the formula:
W = εε0S U2 / (2d).
use capacitors
ability capacitors smoothly collect the electric charge and fast enough to give it is used in various fields of technology.
with an inductor can create oscillating circuits, filters currents, the feedback loop.
Flashlights, stun, which is almost instantaneous discharge capacity of the condenser is used to create a powerful current pulse.Charging the capacitor comes from the DC source.Himself capacitor acts as an element, it breaks the circuit.Discharge occurs in the opposite direction through the lamp small ohmic resistance almost instantly.The Taser this element is the human body.
capacitor or battery
ability long time to keep the stored charge gives you a great opportunity to use it as a storage device or storage of energy.In radio This property is widely used.
Replace the battery, unfortunately, the capacitor can not, because it has a feature of discharge.Accumulated their energy does not exceed a few hundred joules.The battery can store a large supply of power for a long time and with almost no loss.
