Is Plate Capacitor Gap a "Non-linear" Medium?

In summary, the conversation discusses the possibility of the space between two DC charged parallel plates being a non-linear medium with respect to an EMF radiated by a coil within that space. It is noted that this would only occur near the breakdown potential, and that most real capacitors are close to linear within their designed parameters. The effects of dielectric materials and AC signals are also considered. The idea of using a coil between charged plates to simulate a ferroelectric dielectric is proposed. There is also a discussion about the linearity of capacitors and the potential impact of inserting a coil within a capacitor.
  • #1
Fluxation
21
1
Could the space (air gap) between two DC charged parallel plates be considered to be a "non-linear" medium with respect to an EMF radiated by a coil contained within that space?
 
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  • #2
Fluxation said:
Could the space (air gap) between two DC charged parallel plates be considered to be a "non-linear" medium with respect to an EMF radiated by a coil contained within that space?
Only if the PD were very near the breakdown potential. Superposition applies over a huge range of Field Strengths and Air is more likely to be linear (in the limit) than any solid dielectric, I think.
 
  • #3
In practical HV applications, the inner surfaces of the flat capacitor plates would probably be covered in a material such as mylar or kapton sheet. As I understand its molecules would be distorted by the superposed ES field gradient.

Would this of itself not give rise to some form of non-linearity with respect to intersecting EMF's?

Although not germaine to the OP, it might also be pointed out that in a spherical or cylindrical cap the charge distribution itself is non-linear.

All this no doubt becomes more complex if AC instead of DC is applied.

Comments?
 
  • #4
An ideal capacitor is linear, by definition. Any nonlinearity is a defect in the capacitor.

Most real capacitors are pretty close to linear if operated within their designed parameters.
 
  • #5
There appears to be a difference of opinion on this since the charge/discharge curves of a cap are exponential. There is no straight line relationship between V and I unless plotted together.

The dielectric material also needs to be factored in. Does it have ferroelectric properties?

http://www.eecg.toronto.edu/~ali/ferro/model.html

Here is a thought. What would happen if I sandwitched a flat spiral coil of insulated wire between two oppositely charged disks and fed it with a non-repetitive signal?

Could such a configuration be used to simulate a ferroelectric dielectric?
 
  • #6
Fluxation said:
There is no straight line relationship between V and I unless plotted together
The defining equation ##i=C\frac{d}{dt}v## is a linear differential equation. As I said above, a capacitor is linear by definition
 
  • #7
I did not mean to disagree with you, but was rather inquiring about any predictable effect upon the ideal linearity of a plate cap that might be caused by insertion within it of an EMF radiating coil.
 
  • #9
Fluxation said:
an EMF radiating coil.
I think you mean an EM radiating coil. It's not appropriate terminology to talk of radiating an EMF.
 

1. What is a plate capacitor gap?

A plate capacitor gap is the distance between two parallel plates in a capacitor. It is the region where the electric field is strongest and where the charges are stored.

2. How is the plate capacitor gap related to non-linearity?

The plate capacitor gap is related to non-linearity because it can cause a non-linear response in the capacitor. When the electric field between the plates becomes too strong, the material between the plates can become non-linear, meaning that it no longer follows Ohm's law and the relationship between voltage and current becomes more complex.

3. What is a non-linear medium?

A non-linear medium is a material that does not follow Ohm's law, which states that the current through a conductor is directly proportional to the voltage across it. In a non-linear medium, the relationship between voltage and current is more complex and can change depending on the strength of the applied electric field.

4. How does the non-linearity of the plate capacitor gap affect its performance?

The non-linearity of the plate capacitor gap can affect its performance by causing changes in the capacitance of the capacitor. As the electric field becomes stronger, the capacitance may decrease, leading to a decrease in the amount of charge that can be stored in the capacitor. This can affect the overall function of the capacitor in electronic circuits.

5. Are there any practical applications of non-linear plate capacitors?

Yes, there are several practical applications of non-linear plate capacitors. One example is in radio frequency (RF) circuits, where non-linear capacitors can be used to filter out unwanted frequencies. They are also used in high voltage applications, such as in power supply circuits, where their non-linear response can help regulate the output voltage. Non-linear plate capacitors are also used in nonlinear optics, which is the study of how light interacts with non-linear materials.

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