- #1
sankalpmittal
- 785
- 15
I understand that the dielectric constant of a perfect isolated charged conductor is infinite when its placed in an electric field (generally uniform)... Now I also know that when a conductor is placed between a parallel plate capacitor such that the distance between two plates in those capacitors is completely filled by the conductor, the capacitance of that capacitor becomes infinite, because capacitance of a capacitor when a dielectric medium is placed between it is given by :
C=εoA/(d-t+t/K)
Where, εo is permittivity of free space, A is area of the plate of the capacitor, d is distance between two plates of the capacitor, t is thickness of the dielectric medium placed between the capacitor, K is dielectric constant of the medium.
Now if conductor fully occupies, K=∞ and t=d
Hence we get, C=∞.
Now here are my doubt:
Capacitance is defined as the tendency of conductor to "hold" the charge so that it can be accumulated. Now a conductor has no tendency to "hold" charge.(I am taking the case as above , a conductor occupies all space between capacitor. Hence there can be no induction.) It just passes over the charge across it. Hence logically its capacitance should be 0, but its infinite. Why ?
Same case here:
Suppose I connect a capacitor across a battery. If we observe the part of a wire which is resistance free and there is no other thing, what will be its capacitance across the parts ? Zero or infinite ? Also what will be the potential difference across the part of wire simply ?
Please help !
Thanks in advance...
C=εoA/(d-t+t/K)
Where, εo is permittivity of free space, A is area of the plate of the capacitor, d is distance between two plates of the capacitor, t is thickness of the dielectric medium placed between the capacitor, K is dielectric constant of the medium.
Now if conductor fully occupies, K=∞ and t=d
Hence we get, C=∞.
Now here are my doubt:
Capacitance is defined as the tendency of conductor to "hold" the charge so that it can be accumulated. Now a conductor has no tendency to "hold" charge.(I am taking the case as above , a conductor occupies all space between capacitor. Hence there can be no induction.) It just passes over the charge across it. Hence logically its capacitance should be 0, but its infinite. Why ?
Same case here:
Suppose I connect a capacitor across a battery. If we observe the part of a wire which is resistance free and there is no other thing, what will be its capacitance across the parts ? Zero or infinite ? Also what will be the potential difference across the part of wire simply ?
Please help !
Thanks in advance...