# conductivity Definition and Topics - 31 Discussions

The thermal conductivity of a material is a measure of its ability to conduct heat. It is commonly denoted by

k

{\displaystyle k}
,

λ

{\displaystyle \lambda }
, or

κ

{\displaystyle \kappa }
.
Heat transfer occurs at a lower rate in materials of low thermal conductivity than in materials of high thermal conductivity. For instance, metals typically have high thermal conductivity and are very efficient at conducting heat, while the opposite is true for insulating materials like Styrofoam. Correspondingly, materials of high thermal conductivity are widely used in heat sink applications, and materials of low thermal conductivity are used as thermal insulation. The reciprocal of thermal conductivity is called thermal resistivity.
The defining equation for thermal conductivity is

q

=

k

T

{\displaystyle \mathbf {q} =-k\nabla T}
, where

q

{\displaystyle \mathbf {q} }
is the heat flux,

k

{\displaystyle k}
is the thermal conductivity, and

T

{\displaystyle \nabla T}
is the temperature gradient. This is known as Fourier's Law for heat conduction. Although commonly expressed as a scalar, the most general form of thermal conductivity is a second-rank tensor. However, the tensorial description only becomes necessary in materials which are anisotropic.

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1. ### Changing the k constant in voltage potential equation?

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2. ### Tank Heat Transfer

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3. ### I Is a Copper Conductor Directional?

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4. ### Sophisticated Experiment (Thermal Conductivity of Housing Materials)

Hi everyone, I am currently a third year University Student in the UK and I'm in the midst of doing my dissertation. My dissertation topic (Effective methods of decreasing the thermal Conductivity of Housing Materials) requires that I produce several experiments to test and analyse a certain...
5. ### I Understanding L&L's argument, constant current in a crystal

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6. ### Band diagram, conductivity tensor

Hello! Does anyone have an idea of how can I obtain information from a band diagram about the directions along which the system conducts best and worst ? Thank you in advanced! :)
7. ### A Conductivity and Integration over Fermi-Sphere?

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8. ### Crystal Symmetry Problem

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9. ### B 4 Questions About Lenz's Law Experiment

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10. ### Calculating the conductivity of a solution of HCl and HAc

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11. ### Fourier Conduction Law

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12. ### Conductivity of an electrolyte

I know that electric conductivity of metallic conductors increases with decrease in its absolute temperature(kelvin) . But is it the same for electrolytes such as water. Is cold water a better or worse conductor of electricity than warm water at same pressure and concentration.
13. ### Thermal Physics: Conduction

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14. ### B Equation for Conductivity of Aqueous Solutions

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15. ### Current flow on the surface of a permeability bigger than 1

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16. ### How should I calculate conductivity

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17. ### What does Griffith mean by this hint? [Electrodynamics]

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18. ### A How possible is LDA DOS not consistent with experiment?

Usually one would expect through \sigma=ne^2 \tao/m and DOS~1/m to argue that \sigma ~ DOS around Fermi surface. This seems to be a quite fundamental argument and should be expected to hold most of the time. For a quality check, does anybody have experience on how often LDA gives consistent DOS...
19. ### Graphite touch button

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20. ### A Where can I find data on electrical conductivity?

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21. ### Conductivity of saltwater dielectric vs current

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22. ### Conductive Silicon Carbide [Carborundum]

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23. ### Hydraulic conductivity Units

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24. ### Are a substance's electrical and heat conductivity related?

For example can an object be very conductive to electricity but be a very poor conductor of heat and vise-versa, or is a good conductor of one always a good conductor of the other and a bad conductor of one always a bad conductor of both? If they are related, then how and why are they connected...
25. ### Making Carbon pellets with PVA

Hey there. I am making Carbon pellets using polyvinyl alcohol as a binder to help shape the pellets. I would like to measure the pellet's conductivity without being hindered or influence by the conductivity of the PVA. One way to do it is to heat the pellets to 300 degrees and evaporate the PVA...
26. ### Electrical conductivity of seawater depends on salinity how?

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27. ### Thermal Physics: Cooling by both Conduction & Convection

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28. ### How to test a 1.5 pound magnesium anode

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29. ### Parallel electrodes (space charge density, current density)

Homework Statement Two plane parallel electrodes are separated by a plate of thickness s whose conductivity \sigma varies linearly from \sigma_0 near the positive plate to \sigma_0 + a near the negative plate. Calculate the space charge density \rho_f when the current density is J_f ...
30. ### Mobility of 2D material, sigma=N*e*mu with N surface density

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