Can a material have both dielectric and resistance properties?

  • Context: Undergrad 
  • Thread starter Thread starter Apteronotus
  • Start date Start date
  • Tags Tags
    Dielectric Resistor
Click For Summary

Discussion Overview

The discussion explores whether materials can exhibit both dielectric and resistive properties, particularly in the context of their behavior under different electrical conditions, such as AC and DC. Participants examine the implications of these properties in practical applications, including capacitors.

Discussion Character

  • Exploratory
  • Technical explanation
  • Debate/contested

Main Points Raised

  • One participant questions if materials can possess both dielectric and resistance properties, suggesting that current flow and polarization may occur simultaneously.
  • Another participant agrees that some materials exhibit both properties, especially at high frequencies, where dielectric polarization can lead to significant losses due to resistive components.
  • A participant provides an example of pure water being used as a dielectric in capacitors, noting its high permittivity and the challenges posed by its conductivity over time.

Areas of Agreement / Disagreement

Participants express varying views on the relationship between dielectric and resistive properties, with some agreeing on their coexistence in certain materials, while others highlight specific conditions under which these properties interact differently. The discussion remains unresolved regarding the implications of these properties in practical applications.

Contextual Notes

Participants mention the complexity of dielectric behavior at different frequencies and the influence of material purity on resistance, indicating that assumptions about ideal behavior may not hold in all cases.

Apteronotus
Messages
201
Reaction score
0
Hi,

Do material posses both dielectric as well as resistance properties?

I imagine that when there is a difference in potential across a volume of some material, some current will flow (I=V/R <-- the material's resistance), but also the material may become polarized to a certain degree (dielectric property). Is this true? Am I on the right track?

Thanks,
 
Physics news on Phys.org
Apteronotus said:
Hi,

Do material posses both dielectric as well as resistance properties?

I imagine that when there is a difference in potential across a volume of some material, some current will flow (I=V/R <-- the material's resistance), but also the material may become polarized to a certain degree (dielectric property). Is this true? Am I on the right track?

Thanks,

Yes, the two are important, taken together in some materials. This is particularly important when high frequency AC is concerned and an insulating material (dielectric) is constantly being polarised in different directions. Take, for instance, a cheap Capacitor that works fine at 1MHz. The 'resistive' component of the dielectric can produce serious losses at 100MHZ or higher. (But I think this is the 'inverse' of your actual question.)
Where DC is concerned, the valence electrons in a metal will move readily, so the electric field will be small - and, hence, the other electron orbitals will not be altered significantly (which is what is implied by 'polarisation'). In semiconductors or some impure mixtures, the internal fields when conducting DC could be enough to produce some distortion of the molecules but it would be very difficult to detect this effect at DC.
The idea of this complex dielectric constant is essentially something relevant to AC.
 
And yes from my location as well. Sophiecentaur and I seem to live in places where laws of physics show great similarities.

One example: very pure water is used for a limited time as a dielectric, to store amazing amounts of energy. It was done in the previous version of the Z-machine (have a search, it's fun) because water has a very good breakdown field over a short time and a huge permittivity around 80, making capacitors compact. It's also cheap enough to fill a complete pool, even when de-ionized, so said capacitor, charged at several MV, makes a really nice ZAP.

But if someone tries to keep the charge for too long, then the resistance (the conductivity) gets annoying and discharges the water capacitor.
 
Thank you both. :)
 

Similar threads

Graduate How does dielectric heating actually work?
  • · Replies 1 ·
Replies
1
Views
2K
Graduate Maxwell's Equations, Dielectrics, Auxiliary Fields D and H
  • · Replies 16 ·
Replies
16
Views
3K
Undergrad Why does increasing resistance in a conductor decrease power dissipation?
  • · Replies 7 ·
Replies
7
Views
2K
Undergrad Griffith, Electrodynamics, 4th Edition, Example 4.8. (Second part)
  • · Replies 3 ·
Replies
3
Views
872
Graduate Cause of multiple paths of electrical breakdown?
  • · Replies 5 ·
Replies
5
Views
2K
Graduate Dielectric material becomes conductive at High Frequency?
  • · Replies 5 ·
Replies
5
Views
7K
Graduate Charge distribution in a resistor with a current
  • · Replies 4 ·
Replies
4
Views
17K
Undergrad EM Radiation of "Permanent" Molecular Electric Dipoles
  • · Replies 1 ·
Replies
1
Views
2K
Graduate Resolving an Infinite Sheet of Charge in Dielectric Material
  • · Replies 7 ·
Replies
7
Views
9K
Graduate Capacitor transient response, what happens in the dielectric?
  • · Replies 3 ·
Replies
3
Views
3K