Tuesday, 8 October 2013
How Capacitor Work?
In general you must have now
understood what is a capacitor? But there are still numerous different
complicated ways through which a capacitor may be configured. Hopefully you
will get to read them in my forth coming articles.
 |
| Various Capacitors |
A capacitor (originally known as condenser) is a passive two-terminal electrical component used to store energy in an electric field. The forms of practical capacitors vary widely, but all contain at least two electrical conductors separated by a dielectric (insulator);
for example, one common construction consists of metal foils separated
by a thin layer of insulating film. Capacitors are widely used as parts
of electrical circuits in many common electrical devices.
How Does a Capacitor role?
From
the symbol of a capacitor we notice that, it has two plates or poles separated
by a space. A capacitor is just prepared up that way practically. A capacitor internally consists of two
conducting plates separated by an insulator or the dielectric.
Working principle:
When a voltage (DC) is applied to its pair of conducting plates, an electric
field is generated across them. This field or energy is stored across the
plates in the form of charge. The relation between voltage, charge and the
capacitance is expressed through the formula:
C = Q/V.
Where C = Capacitance, Q = Charge
and V = Voltage.
So
it can be clearly understood from the above formula that the potential drop or
the voltage across the plates of a capacitor is proportional to the
instantaneous charge Q stored in the capacitor. The unit of measurement of
capacitance is Farad. The value of a capacitor (in Farads) depends on the
amount of charge it can store in it.
What
is the uses of capacitor ?
In electronic circuits, capacitors
are usually used for the following purposes:
Filter AC: A power supply circuit may be rendered useless without a
filter capacitor. Even after full wave rectification, the voltage of a power supply may be full of ripples. A
filter capacitor smooths down these ripples and fills up the voltage” notches”
or gaps by discharging its internal stored energy. Thus the circuit connected
to it is able to receive a clean DC supply voltage.
To
Block DC: A very interesting character of capacitors is to
block DC (Direct Current) and allow AC (Alternating Current) to pass
through it. The internal operation of many complicated electronic circuits
involves the use of frequencies which are in fact small alternating
voltages. But since every circuit requires a DC to be useful, sometimes it
becomes very essential to block it from entering the restricted areas of
the circuit. This is effectively countered using capacitors which allow
the frequency part to pass and block the DC.
To
Resonate:
As shown in the adjoining diagram, a
capacitor when conjugated with an inductor will resonate to a particular
frequency which is fixed by their values. In simple words the pair will respond
and lock to a particular external applied frequency and will start oscillating
at the same frequency itself. The behavior is well exploited in RF circuits, Transmitters, metal detectors etc.
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