The conductance of a material sometimes directly proportional to each other, sometimes inversely proportional to each other. what kind of relationship will be between capacitance and conductance?
capacitance C=1/jw and inductance L=jw, where w=2*pi*f. So capacitance has a reverse relation with frequency f and lead phase shift till -90 degree but inductance direct prportional with frequency and lag with +90 degree.
There is no direct relation between capacitance and conductance. The effect of these two on each other depends on situation. In a classical capacitor, made of ordinary dielectric material, the high conductance causes internal leakage of the capacitor resulting in lower capacitance. In a super capacitor, the charge is accumulated inside the capacitor via ionic transport and intercalaction of ions into the active material structure. Hence, higher conductivity is needed for higher capacitance.
I agree with both previous answers but I would also like to add a different perspective on it.
Conductance is related to the resistance of the material (G=1/R). As a result conductance has no dependency to frequency and it is responsible for losses ( I^2.R ).
On the other hand capacitance is due to material dielectric properties and packaging. As a result of capacitance, energy is stored in the form of electric field. In the frequency domain, capacitors are responsible for negative impedance which is inversely proportional to frequency. Zc=1/(jwC)=-j/(wC) , where w=2pif and j=sqrt(-1).
You can also find some characterization of capacitive properties:
https://www.researchgate.net/publication/281202416_Comparative_Study_of_Metal_Oxide_Varistors_MOVs_for_Failure_Mode_Identification
Thesis Comparative Study of Metal Oxide Varistors (MOVs) for Failur...
The electrical Capacitance C (=Q/V) is defined as, the ratio of the electric charge Q (=dq) on each conductor plate of a Capacitor, to the potential difference V between them. Also, the electrical conductance G (=i/V) is defined as, the ratio of the electric current i (=dq/dt) to the potential difference V. For the simple case of an ideal (lumped element) Capacitor, we can write, for its Capacitance C : C = Q/V = integral(i*dt)/V ~ integral(G*dt).
So, a special (integral) relation between capacitance C and conductance G, for the exclusive[1] case[2] of a lumped (and ideal) Capacitor, is :
C = integral( G * dt ).
1. An EIS measurement is recommended for the other cases and the sophisticated circuits.
2. This simple method (in time domain) is used, by some low cost DMM (Digital Multimeters with Capacitance meter), to measure the Capacitance value of a (lumped) Capacitor. Note : discharge the Capacitor before the measurement.
Dear Prof Ioannis Samaras
I think the relation is not correct because you have written the conductance formula (that describes a conductive element) for a purely reactive element (an ideal capacitor).
C = integral( G * dt ) means that the capacitance of the ideal capacitor increases upon time for any non-zero conductance, until storing infinitive charge in sufficiently great time.
On the other hand, consider a fully charged ideal capacitor. The current doesn't flow anymore because the ideal capacitor is fully charged. So, we have zero conductance because there is no current. According to C = integral( G * dt ), we would have zero capacitance for a fully charged capacitor.
Regards
Dear Hamid,
I guess, we (all) accept, that C has a (single fixed,) constant value, for an ideal capacitor (model); it's value is near the (constant value of the) definite integral( G * dt ), in the interval T1 (say, T1=0) and T2. However, you have to acknowledge, that :
1) G is, literally dictated as, G(t), e.g. it is a function of the time, and
2) the G(t-->oo) --> 0 or Lim [ G(t) ] = 0, as t-->oo (infinite), since, the developing (internal electric) field of the capacitor becomes, finally (as t-->oo), the same (and opposite, in sign) to the external electric field.
So, when t-->oo, then, Lim[ i(t) ] = 0, at the end of charging; then, the
Lim [ i(t)/Vconstant,external ] = Lim [ G(t) ] = 0 .
Regards
Rajamanickam Ragavan capacitance and conductance are separate properties in electrical circuits. Capacitance refers to a component's ability to store electrical charge, while conductance represents its ability to conduct an electric current. Generally, there is no direct relationship between capacitance and conductance. However, in specific circuit configurations, an increase in capacitance may lead to a decrease in effective conductance, such as in the case of a low-pass filter. Nevertheless, this relationship is not fundamental and depends on the circuit and component characteristics. Overall, capacitance and conductance are considered independent properties in most electrical systems.
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