draw capacitance frequency characteristics?

Question

Capacitance is a passive component.the value of capacitance varies as frequency varies

Answer 1

The capacitance of any non-adjustable capacitor is fixed. It doesn't change. What happens is that the capacitive reactance is different for different frequencies. In general, the higher the frequency, the lower the capacitive reactance. In othe words, a higher frequency signal will have less loss passing through a given capacitor than a lower frequency signal.

But this depends on the construction of the capacitor. If you operate outside of the frequency design range, the signal loss may reach a point where it increases with increase in frequency.

A large electrolytic capacitor designed to filter the hum of a power supply may start showing strange results if a frequency that is too high is applied to it. The conductors of the electrolytic capacitor are wound around each other, kind of like a roll of toilet paper. At some point this wrapping may begin to show an inductive reactance as the frequency is raised.

Answer 2

Check a basic electronics text book or

http://en.wikipedia.org/wiki/RC_circuit