A capacitor acts like a short circuit to ac, depending on the
frequency of the ac signal and the value of the capacitor, therefore
noise can be short circuited to ground with this characteristic, thus
reducing it's noisy effect on the rest of the circuit. At the same
time allowing the DC component within the signal to remain unaffected.

"ameet" wrote in message
om...
Now that I have heard that capacitors "allow" ac signals but "block"
dc signals as below.

Xc=1/[2(pi)(Fc)],

Fc=frequency of signal.

Now for dc signals Fc=0 Hz sothat Xc~infinity which implies that it
is
open circuited,so we conclude that capacitor blocks dc signals and
allows ac signals(as they have a definite value of Fc).


But the problem is he Why do we use capacitors in radio circuits
to
"block" noise signals which are nothing but ac signals?????

Can any one please explain where I am going wrong?????