Hi again,
Do you know what mesh analysis and nodal analysis are?
Here's an example of dual circuits:
Circuit1:
A voltage source E in series with a resistor R also in series with a capacitor C. The voltage across the cap is vC.
Circuit2:
A current source in parallel to a conductance G also in parallel to an inductor L. The current through the inductor is iL
In circuit 1 we had E,R, and C, and looked at vC, and in circuit 2 we had I, G, and L, and looked at iL.
The circuit 2 elements are related to circuit 1 elements as:
I=E
R=1/R
L=C
iL=vC
So to convert to the new circuit we would use a current source equal to E amps, a resistor equal to 1/R, and an inductor equal to C, and the output would be iL. The response iL(t) would be the same as the voltage response vC(t).
Example:
We have three elements in series, a voltage source E=1v peak, R=100 ohms, and C=100uf, and the dual is a circuit with three elements in parallel, a current source I=1 amp peak, R=1/100 ohms, and L=100uH.
The response of the voltage across the cap in circuit 1 is the same as the current through the inductor in circuit 2. With a frequency of 100Hz, the cap voltage (circuit 1) is about 157mv and the inductor current (circuit 2) is about 157mA.
This illustrates that if you want to change a circuit from using a capacitor to a circuit using an inductor you have to use the same value inductor as the capacitor, a resistance equal to the reciprocal of the original resistance, and change the voltage source to a current source.
Does that help?
It might help more if you told us exactly what circuit you are dealing with and what you want to change to save space or money. In many cases a dual circuit will not work for a number of reasons, even if you swap exactly, because there are other characteristics that change when you go from a cap to an inductor. It really has a lot to do with the actual application.