Capacitors are electronics materials that are made up of two metal plates separated by a dielectric or insulated material.
All form of capacitors are used to store charges in circuits,they are also called lyden jars or condensers.
when capacitors are connected to a DC current it doesn't allow the flow of electricity because of the insulating material also known as dielectric substance, however if connected to an AC power source it allows flow of current without any resistance.
In circuit diagrams,capacitors are represented as two upright strokes of equal length indicating metal plates as shown below.
How do capacitors stores charges?
Capacitors stores electricity with the help of two separate metals separated by an insulator,when connected to a power source electrostatic charges are formed at the plates.
Capacitance of a capacitor.
Capacitance is the amount of charge a capacitor can hold or time taken to supply electrons to a load. capacitance is measured in farad.
Mathematically, Q=CV,
Q denotes charge,
c=capacitance,
V=voltage.
capacitance depends on the
a.size of the metal plates,
b.the distance between the plates
c.and the dielectric material use to separate them.
It tends to have great capacitance with a good insulator than ordinary air.
The capacitance of a capacitor is measured in farad named after the British scientist "Michael Faraday" ,common units includes;1000uf,2.2pf,100uf and 1nf etc.
This means that an 100uf capacitor has much capacitance than a 2.2uf capacitor.
For example when a 1000uf capacitor is fully charged with a battery,and connected to an LED,it glows and then dies down slowly.It takes the capacitor some seconds to continue lightning up the LED before going down, therefore the larger its capacity the longer it lights or power a load.
capacitance values and their prefix.
Capacitance values are written in prefix to reduce long figures,they includes;
1.Micro farad (μF)= 0.000001μF (10^-6μF).
2.Pico farad (pF)= 0.000000000001PF(10^-12pF)
3.nano farad(nF)=0.000000001nF
(10^-9nF).e.t.c.
Capacitors circuit connection.
Capacitors can be connected together in a circuit either to;
a.reduce capacitance
When capacitors are connected in series i.e end to end as shown in the diagram above,their capacitance reduces.To calaculate the capacitance in series
CT(total capacitance)= 1/c1+1/c2+1/c3+..........
b.to increase capacitance.
they are also connected together in parallel as indicated above to increase capacitance thus cT=c1+c2+c3+................
Capacitors voltage rating.
All types of capacitors are usually marked with their voltage rating.
when a circuit voltage is for example 25V,the capacitor working voltage to be used must be twice the voltage applied to it e.g 50V.
Working voltage (WV) means the highest voltage a capacitor can accept.WV depends on the thickness of the plates and the nature of dielectric material used.
When high voltage are applied to capacitors,they explode and become shorted.
Applications of capacitors.
Capacitors has many applications in circuits such as
1.regulating flunctating DC current, filltering DC from alternating current during rectification and removing humming sounds.
2. used to reduce Sparks in induction heaters of cars.
3.Its ability to block DC currents enables capacitors to be used to smooth the output voltages of power supplies and remove unwanted signals during transmission that would otherwise cause damage or false triggering of semiconductors and digital components.
4.Capacitors are mostly used to tune the frequency channels of a radio receiver circuits
Beginners Introduction to capacitors summary
We have all learnt in this tutorial that what a capacitor does is to store electrical charge on its plates. The amount of electrical charge that a capacitor can store on its plates is known as its Capacitance value and depends upon three factors;
1.dielectric material;the type of material which separates the two plates called the “dielectric”, the higher the insulating powerof the dielectric the greater the capacitance.
2.Surface area of the plates; the larger the two conductive plates which make up the capacitor, the larger the area the greater the capacitance.
3.Distance between plates; the larger the distanc between the two plates, the smaller the distance the greater the capacitance.
Tags:
Basic Electronics.