Multiple electrodes - capacitance.

In summary, the conversation discusses finding the capacitance on three electrodes placed inside a pipe with one electrode giving out a certain voltage and the dielectric constant of the material between them known. The speaker also asks for hints and resources on the topic. The conversation also clarifies that the electrodes are rectangular plates and that the capacitance can be measured using a capacitance meter or an oscilloscope. The formula for capacitance is also mentioned.
  • #1
Dafe
145
0
Hey,
I have a length of pipe. Inside the pipe walls I have placed four electrodes. If one is giving out
x volts, and I know the dielectric constant of the material between them, is there an easy way of finding the capacitance on the other three electrodes?

I'm looking for hints as well as good resources on the subject.

Thank you.
 
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  • #2
It really depends on the geometric placement.

What's an electrode?
 
  • #3
By electrodes I mean plates of some metal.

Let's say the plates are facing each other if you know what I mean..
 
  • #4
Dafe said:
By electrodes I mean plates of some metal.

Let's say the plates are facing each other if you know what I mean..

You're language is hard to follow, but you should elaborate more. Are they stacked like coins with some space in between? What's the spacing.

The "capacitance on them" doesn't mean anything. You might validly ask about the capacitance between two plates (or electrodes). Each plate can have a voltage relative to some other plate. The pipe itself is a "plate".
 
  • #5
Let's say that the pipe is made of glass.
I make four rectangular shapes of some metal.
I glue them inside the pipe walls.
I have a battery connected to one of the metal shapes.
Can I then find out the capacitance on the other metal shapes?

Is this a better explanation?

Thank you for your patience!
 
  • #6
C = e(A/d)

For d is small compared to the size of the plate:

C is the capacitance between[i/] two plates.
e is the dialectric constant of the material
A is the area of a plate
d is the distance between them
 
  • #7
What if d is not small compared to the size of the plates?
 
  • #8
Then the simple formula Phrak gave is not accurate. You would have to measure the capacitance.

It can be measured with a capacitance meter (some DVM's have that feature). Or measure the time to discharge the cap through a resistor by measuring the capacitor voltage during discharge -- either with a DVM if the discharge time is longer than several seconds, or on an oscilloscope if the discharge time is shorter.

From your description, it sounds like you would a capacitance meter or an oscilloscope -- discharge time should much faster than 1 sec if d is the thickness of a glass pipe.
 

1. What is the purpose of using multiple electrodes in capacitance measurements?

The use of multiple electrodes allows for a more accurate and precise measurement of capacitance. By using multiple electrodes, the electric field is distributed more evenly, reducing errors and providing more reliable results.

2. How do multiple electrodes affect the sensitivity of capacitance measurements?

Multiple electrodes increase the sensitivity of capacitance measurements. This is because the electric field is stronger and more evenly distributed, allowing for a more precise measurement of small changes in capacitance.

3. Can multiple electrodes be used to measure capacitance in different materials?

Yes, multiple electrodes can be used to measure capacitance in a variety of materials. However, the type and arrangement of electrodes may need to be adjusted depending on the material being measured.

4. How do the distance between multiple electrodes affect capacitance measurements?

The distance between multiple electrodes can have a significant impact on capacitance measurements. A larger distance between electrodes will result in a weaker electric field and a lower capacitance value. On the other hand, a smaller distance between electrodes will result in a stronger electric field and a higher capacitance value.

5. Can multiple electrodes be used for non-contact capacitance measurements?

Yes, multiple electrodes can be used for non-contact capacitance measurements. This is particularly useful in situations where direct contact with the material being measured is not possible or undesirable. Non-contact capacitance measurements can be made using techniques such as proximity sensing or capacitive coupling.

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