Electro-Conductivity Layer Question

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The discussion centers on the total conductivity of multiple layers with different conductivity values, all of equal thickness and in intimate contact. The proposed formula for total conductivity, 1/sigmatotal = 1/sigma1 + 1/sigma2 + ..., is confirmed to be correct. This equation parallels the rules for resistors in parallel and capacitors in series, as conductivity is the inverse of resistance. The conversation also touches on the relationship between resistance and conductivity, emphasizing that they can be treated similarly in calculations. Overall, the participants agree on the validity of the approach to calculate total conductivity for layered materials.
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Given different conductivity values, sigma1, sigma2, etc.

Given the thicknesses are the same.

Given the layers are in intimate contact with each other. (No air gaps.)

Is the whole conductivity for the stackup of layers follow this:

1/sigmatotal = 1/sigma1 + 1/sigma2 + ... ?

Is this correct?

Is this the same equation as resistors in parallel, capacitors in series, conductors in thermo?

I don't know (more like I can't remember - E&M and thermo years ago) and would appreciate the help. Thank you.
 
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T.Swede said:
Given different conductivity values, sigma1, sigma2, etc.

Given the thicknesses are the same.

Given the layers are in intimate contact with each other. (No air gaps.)

Is the whole conductivity for the stackup of layers follow this:

1/sigmatotal = 1/sigma1 + 1/sigma2 + ... ?

Is this correct?

Is this the same equation as resistors in parallel, capacitors in series, conductors in thermo?

I don't know (more like I can't remember - E&M and thermo years ago) and would appreciate the help. Thank you.

No physics majors? :smile: I'm not trying to trip anyone up. I am being sincere. Should I reword the question? How about this:

Take several metals of different conductivity, with the same thickness, intimately layered on each other. What is the total conductivity?

Should I try another forum? Anyone that I could ask would be appreciated? Thank you.
 
Hi there Swede. No physics major, but I hope my electronics major will do ^^. That seems correct. If you want to look at it from another view point. Consider that conductivity is the inverse of resistance, so...

conductivity = 1/resistance

And the resistance add up rule is:

Rtotal = R1 + R2 + R3 + ...

Then why not have the conductivity addup rule be:

1/Ctotal = 1/C1 + 1/C2 + 1/C3 + ... (since R1 = 1/C1, R2 = 1/C2 ...)

And yes, as far as I can remember, it is the same equation for capacitors and conductance in thermodynamics =D
 
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