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Uses of Capacitors

9/9/2013 8:22:45 AM | by The Green Book


Capacitors are electrical components that electrostatically store energy in an energy field. It does this by storing electrons. They are used in most electronic devices as part of their circuits.


Capacitors can have high frequency uses or might be better suited to high voltage uses. This is determined by the size of the capacitor and the material the dielectric is made of. For example, capacitors in radio tuning circuits use air as a dielectric while those that have high frequency purposes, like a radio antennae, use ceramic. Capacitors can be found in vast range of devices, from the standard pocket calculator to the equipment used to deploy space probes by NASA.


How they work


Although there are many different kinds of capacitors which have many uses, all capacitors contain two conducting plates that are separated by an insulating material. This material is called a dielectric. A dielectric can be made from any insulating material, in theory, but often the kind of material used for it ranges according to what the capacitor will be used for.

When a capacitor is placed in an electric circuit, one plate is connected to the battery’s negative terminal and the other is connected to the positive terminal. The one connected to the negative terminal accepts electrons from the battery while the other loses electrons to the battery. Because of this, there is potential difference across the two plates and this develops an electric field across the dielectric. When the battery is removed from the circuit and the circuit is closed again, there will still be current flowing through the circuit, until the stored energy in the capacitor runs out.


Uses of capacitors


Capacitors can release all their energy in less than a second, as compared to batteries that release their energy over minutes. Thus, one use for capacitors is in devices that have a need for high speed charge, such as a camera flash or TV. The battery charges the capacitor over a few seconds and the capacitor dumps all of its charge to power the device. Capacitors also act as a temporary battery and can power devices while the battery is being charged so that important data is not lost.


Another use for capacitors in electric circuits is to eliminate ripples, which happen in a direct current that has been derived from an alternating current. They are small and periodic variations in the power supply and are unwanted because they affect the electronic device, such as making wavy lines appear on a TV screen. Capacitors even out the ripple either by adding or removing voltage.


Also, they block direct currents but allow alternating currents to flow through them. This is because with just a direct current, the current stops flowing once the capacitor is fully charged. With an alternating current, the direction of the current changes periodically, making the capacitor charge and discharge so the current manages to flow through it. This allows the alternating current and direct current components of a signal to be separated.


Safety hazards


Capacitors also have safety hazards. Since they store energy and then dump all of their charge almost instantly, a user could receive an electric shock, even after the power is no longer connected to the device. Other devices that are connected could also be damaged. There are usually safety measures, such as discharging the device with equipment or a built-in safety feature. It is important to ensure the instructions for such devices have been properly read through to prevent accidents from happening.


If capacitors are connected to voltages or currents beyond the rating they were built for, have been worn out or overheated, they could become damaged or even explode, which can be extremely dangerous. The risk of this can be minimized by maintaining the capacitor and properly containing and fusing the capacitor.


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