# signal and capacitor

Discussion in 'Electronic Basics' started by jason, Mar 4, 2005.

1. ### jasonGuest

Hello All

I wish to know what will happen for the case of 1)DC and 2)AC input
power or signal to the capacitor in a circuit.
I heard that capcitor can act as a short or open circuit depending on
DC or AC(in high or low frequency input power signal or signal itself).

Can anyone help to explains this clearer in the point of view from
physics and electronics?

Kindly share
Thank you

rgds and thanks
Jason

2. ### Guest

DC - capacitor block current - infinite resistance
AC - passes thru cap... if w= 0 zero resistance

Regards
Vibhash Chandra Jha

3. ### John PopelishGuest

The relationship between current through a capacitor and the voltage
across it is:

I=C*(dv/dt), where I is current in amperes, C is capacitance in
farads, and dv/dt is time rate of change of voltage in volts per
second.

Since pure DC has zero volts pure second rate of change, the current
is zero. For any other waveform from pulses to sinusoids, there are
various rates of voltage change at different times, so different
instantaneous currents at different times.

4. ### jasonGuest

Thank you All

The explanations are great.

I simply amazed with so much of great answer and help from many people
Thank you so much for who ever written up there to help me
thank you

Jason