# Electro-Conductivity Layer Question

1. Oct 6, 2005

### T.Swede

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.

2. Oct 7, 2005

### T.Swede

No Takers?

No physics majors? 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.

3. Oct 7, 2005

### mezarashi

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

Last edited: Oct 7, 2005