Conductivity Definition and 382 Threads

What is "effective" conductivity? In one of my homework problems (This ISNT a homework help question! It is conceptual) It says to find the "effective" conductivity. What is the difference between conductivity and effective conductivity? Is there any difference?

I want to calculate the average thermal conductivity of UO2 by : 1/(To-Tf) * ∫To->Tf dT K(T) any one can provide me anything about the thermal conductivity of UO2 as function of temperature or any measured data in a range of temperature.

I was wondering whether, making a comparison between the propagation of electric current through a conductor and the propagation of an electromagnetic wave through a dielectric, one could establish the following correspondences: Ability of a material to facilitate the propagation of the...

Hello everybody. I would like to ask the following: Imagine a source of strong electric filed. For example a positively charged metal sphere. Then we put a small (relatively to the source of the electric field) metal object in the electric field. Electron inside the metal move in such way, that...

If we prepare a chain of flourine atoms: F-F-F-F-F-F-F-F-F-F-F-F-F-F-F-F-F-F-F we can construct the band structure shown. I'm using flourine as an example but my question can be generalized: What do we know about the conductivity of a material (such as this 1D chain) when the fermi level lies in...

Hi I've been trying to find effective thermal conductivity of sintered bronze, especially of that used in self-oiled sliding bearings (like Oilite). I need it to know how much less it is compared to dense copper alloys, eg. tin bronze. So far my search has proven fruitless. It seems that...

Homework Statement So you have a fridge, the walls of the fridge are made of aluminum, plastic and insulation. Which is the most relevant and why for the fridge. Homework Equations Thermal conductivity of aluminum=250 Plastic=.03 insulation=0.035 - 0.16 The Attempt at a Solution...

Homework Statement So the outside of a refrigerator is made up of plastic, metal, and insulation? Which is the most important and why. Homework Equations no equation needed. The Attempt at a Solution I thought that the insulation would be the most important because it reduces...

Homework Statement I was wondering why there is such a disparity between thermal conductivty and how they act in the real world. Ex. If if have 3 cups filled with hot water. The 3 cups are made of glass, plastic and metal. The metal will obviously have way higher thermal conductivity...

As we know that conductivity of semicondutors can be increased or decreased by supplying heat or photons to the material. Its said that photoconductivity of the semiconductors is dependent on the wavelength of the light and not on the intensity of the light then how are these used as the...

I was hoping someone could help me with a project I am doing. I have contacted a manufacturing company thatmakes thermal wrap material, and I need to see if this will work for my project. According to the manufacturer the material is 1/16" thick - this info was also given to me by the...

Homework Statement One end of a metal rod is maintained at 100 degrees C, and the other end is maintained at 0 degrees C by an ice-water mixture. The rod is 60 cm long and has a cross-sectional area of 1.25 cm^2. The heat conducted by the rod melts 8.50 g of ice in 10.0 min. Find the thermal...

Hi all, I'm trying to understand exactly what the physical meaning of conductivity/current is in relation to waves. if we have a wave traveling through a conductor, we find that it decays exponentially, i.e. e^{-\alpha z} where \alpha=imag(k)=\omega\sqrt{\frac{\epsilon\mu}{2}}...

A pretty simple question, but I was just wondering if it was possible to be able to do a conductivity titration for a reaction that does not create a solid precipitate and water? I was thinking no because the only reaction that i thought would work for conductivity was an acid-base...

Homework Statement An ice ball is melting in a water bath. Find the time needed for the ice ball to completely melt. Heat transfer is only due to heat conduction. The radius of the ball is R_0=1cm. The temperature of the water in the bath is t=10°. There is an infinite amount of water...

Homework Statement we have a metalic bar with thermal condutivity of 200w/(m*k) it has an area of 20 cm^2 which is in contact with with an heater that delivers 200 W and is at 300ºC. the metalic bar has a thickness of 1cm The two questions are: a) once the system have entered a...

How do I go about deriving the thermal conductivity of graphene (specifically, in the low temperature limit) when I'm given the phonon dispersion relation? I haven't been able to find anything explaining how the dispersion relation relates to the thermal conductivity in materials. (this is...

My wife was asking me if magnets are conductors of electricity and I told her magnetite isn't. Then she asked me if an iron rod, after being magnetized is an electrical conductor. That got me stumped. I am thinking by right it shouldn't affect the electrical conductivity of the iron rod...

Diamond vs graphite by a conductivity? Hello. This is the last question on HW. Q) Diamond and graphite are both made of carbon atoms. Explain why diamond is elecrically insulationg while graphite is a good conductor in terms of type(s) of hybridization of atomic orbitals and bonds in each...

As a semi conductor approaches absolute zero there should be zero conductivity, the thermal energy that electrons acquire is or can be responsible for promoting electrons from the valence band to the conduction band to provide current flow in a semi conductor ( for t>0). My question is...

I mean how can i analysis the thermal conductivity of two structures with their phonon spectrum. thank you!

I would like to know whether Kelvin or KJs matter when it comes down to a material radiating and / or conducting its heat.

Homework Statement i need to find the thickness of the insulating material that is needed to block out the heat that is coming into the room. the area of the affected wall is 3.3m2 the temp in first room is 18 degree celsius while the 2nd room is 45 degree celsius. the thermal...

Can a compound have a high specific heat capacity and be a good thermal conductor, or are these properties mutually exclusive?

I understand that thermal conductivity is W/(m.K) and u-factor is W/m² K. Obviously U factor is energy transfer over an area but how does this compare to thermal conductivity?

Would it be fair to say that permittivity corresponds to the opposition of a material to an electric field, whereas conductivity corresponds to the opposition of a material to the first time derivative of the field? It seems like these two concepts should have some sort of quantitative link, as...

Hi to all Can some one help me for below question: What is different between "isotropic thermal conductivity" with " anisotropic thermal conductivity" ? where and when we must use isotropic or anisotropic ? which one is more accurate? I solve an example in a FEM software and it is...

Thermal Conductivity , k , for water is .1455 cal/sec/ meter * C ( converted watts to cal/sec) Q/t = k* A delta T/ d A= area M2 d = thickness of water/ice boundary layer Suppose I want to calculate time for 100 grams of ice to melt ( 8000 calories absorbed from surroundings by conduction. I...

I'm currently running RELAP5-3D to model a molten salt reactor and I require the thermal conductivity of graphite. Is there anyone that is aware of this value, or can inform me of a proper resource? Thanks!

Homework Statement Hi, I have some values of conductivity in some temperatures. 0.01 at 400 Kelvin 10 at 600 K 70 at 700 K 1000 at 1000 K And I'm asked to find the energy gap of this intrinsic semi- conductor. Homework Equations The Attempt at a...

We have a customer asking us for the thermal conductivity of a product we sell. None of the engineers have that number. I can think of a simple experiment that might do it, but I don't know the math. I want to take a piece of this material (it's a pipe), put a cap on the bottom, then...

Hi, In calculating the conductivity from the Kubo method j_{\mu}=\int dx' K_{\mu \nu} (x,x') A^{\nu}(x') in literature ( e.g. in Condensed Matter Field Theory by Altland and Simons) you find that K_{\mu \nu}(x,x')= Z^{-1} \frac{\delta^2}{\delta A_{\mu}(x) \delta A_{nu}(x')}...

Okay...in my engineering class we have to build an invention. My partner and I are building a conductivity tester. We are using three levels of LED indicators, to tell how conductive the liquid is. I don't want an LED to light up when it isn't supposed to, so I am trying to use an Op Amp voltage...

Hello all, For my project, I am trying to measure the solute concentration of water inside a porous ceramic plate (~2mm in diameter). I am using platinum electrodes. There are two ways I think I could possibly do this. 1) Place two electrodes on the sides of the porous disk 2) Place 4...

Hey everyone! Got an interesting problem here, I am thinking I did it correctly but I wanted to see your opinions. Here is the problem.. A 0.2-m-thick plane wall is constructed of concrete. At steady state, the energy transfer by conduction through the wall is 0.15 kW/m2. The inside...

Homework Statement Ice has formed on a shallow pond, and a steady state has been reached, with the air above the ice at -9.6°C and the bottom of the pond at 5.5°C. If the total depth of ice + water is 2.1 m, how thick is the ice? (Assume that the thermal conductivities of ice and water are...

Homework Statement solve d/dx(kdT/dx)=0 where k is linear function of temperature k=k(0)(1+BT) Homework Equations this is the solution T+BT^2/2=Ax+C The Attempt at a Solution i opened the equation so that it becomes equal to dk/dx*dT/dx+kd^2T/dx^2=0 i subtitute the...

I'm working on a model that needs to calculate the approximate thermal conductivity of a mixture of gases. I'm having trouble finding a model which is being used by one of my sources but is not cited and I can't seem to find a source for it. I'm hoping that someone here might recognize the model...

Also relate to its reactivty? Because I heard that the easier something loses valence e-, the more conductive it is. This also applies to reactivity, because if an atom has its outermost shell filled by only 7 electrons, it would be reactive, and react by losing the valence electron to another...

In the case when heat is flowing at a steady state through two materials with different thermal conductivities, the classic Q/t = A(T2-T1)/ L1/k1 + L2/k2 applies. In this case T2 is fixed and the two different k values are combined. In the case of cooling , Newtons...

I am trying to decide what alloy I should use in an experimental heat transfer device. I am considering 2 materials- 304 Stainless Steel and SAE 516 Grade 70 boiler steel. I want to choose the material that has the best conductivity characteristics. To be clear, I want the material that has...

Homework Statement Design a portable container that will keep medicines at around 4 degrees celcius for at least 12 hours. Homework Equations Fouriers law, q=kA(T1-T2/L) Thermal Resistance=L/kA q=heat transfer rate (in W) K=thermal conductivity (W/M*degrees C) A=cross sectional...

I've searched the net and haven't found an explanation for the term, so hopefully this will now return on searches for people. Besides, I'm confused about the term myself. What is meant by "optical conductivity"? How is it different from say a DC conductivity in J = cE where c is...

Homework Statement Rod of cross sectional area A and length l has its left end held at constant temperature t1 and its right end held at t2<t1. If the conductivity varies with distance from the left end, x, according to the relationship k= x/R + k0 (R and k0 are positive), what is the steady...

I think: Two reasons, bad overlapping orbitals due vibrattions and high electron population in conduction band will decrease conductivity in metals if you increase T.

Hi, I'm new here. As I was designing my IB lab, this idea popped in my head: Although the electrical conductivity of metals (and other solids) decrease as temperature rises, what about electrolytes? For all I know, electrolytes conduct electricity by charged ions, which react with both...

How does shining light on a metal affect it's conductivity? Specifically, I'm wondering about IR light (1.5um) shining on either Aluminum or Gold. My intuition would say that if the metal isn't a perfect reflector and has some absorption, it would increase the number of carriers, thus...

Calculate the conductivity of an intrinsic semiconductor at room temperature and from the following data: (n)Carrier density(where electron=holes)=2.9*10^19 carrier/m^3 Electron mobility = 0.45 m^2/V s Hole Mobility = 0.23 m^2/V s (q)Charge per electron/hole = 1.6*10^-19 coulomb/carrier...

Hello, I'm trying to find a metal that has a conductivity that's about 150% that of stainless steel grade 384. I've been looking for some charts that compare conductivities of metals but all the charts I find seem to have a few discrepancies. Could someone give me a link to a reliable chart...

HI I would like to test the thermal conductivity of r wall by K=Q*d/ A (t2-t1) K =conductivity d+=thickness A= area Q= heat flow my problem how I could simulate heat in my experiment and how I will measure the heat flow? could you please help me. Kind regards