Conductivity Definition and 382 Threads

This question pertains to the (non)relationship between thermal conductivity, specific heat, human perception and thermosensors. Here goes: Let's say I place four thermosensors on my body. Then, on top of these thermosensors I place four different items (A, B, C, and D). All four items start...

Hello all, I am not an engineer but am trying to learn finite element analysis for solid materials - in particular heat conductivity for time dependent problems in 2-D for a single material. I am interested in the explicit Euler time marching, thus I believe I need a lumped capacity matrix...

Exterior commercial frames (.053") embedded in a concrete wall 8" thick with 3" layers of polystryrene (3# density) on each side of concrete cavity. Frame rests on foam inside and outside of building. Frame is grouted solid with poured in place concrete. Is there an appreciable (to be...

I'm wondering how one would go about measuring the conductivity of a semiconductor with variation in temperature, I assume the non ohmic behaviour prevents one from making simple voltage current measurements and then inferring resistance and the conductivity...any answers much appreciated...

Please Help, I am not an mechanical engineer but am trying to learn Finite Element Methods to solve a 2D Steady State Heat Conductivity problem. Can anyone point me to an exact solution to the 2D Heat conductivity problem? Please be gentle, I have not had a physics class since 8th grade...

Does anyone know where I could find a good chart listing the thermal and electrical conductivities of metals? The chart doesn't need to be terribly accurate, I only need to know general values for comparison to other metals on the chart. All I need is one basic value for each metal. If anyone...

Heres the question: A sample of pure silicon, which has four valence electrons is doped with gallium, which has three valence electrons, to give a concentration of 10^23 m^-3. a. Is the material n-type or p-type? b. If the electron mobility is 0.14 m^2/Vs and the hole mobility is 0.05...

Hi :) I'm having difficulty with finding the relationship between specific heat, c, and thermal conductivity, k and cannot answer these questions - Six objects are placed in a 500 F (260 C) oven and allowed to reach thermal equilibrium. Each object has a mass of 1.0 kg . The specific heat and...

Can anyone tell me at what speed an electrical signal travels through copper wire? How about fibre optic cable? (I'm REALLY new here). Thanks.

Homework Statement This is my first post on these forums, this problem is part of a lab and its part my end of year result but we never did anything on it in class so i have'nt a clue how to do it. Help would be really appreciated The handle of a freezer door 12cm thick is attached by two...

Homework Statement A wall is insulated with glass wool of thermal conductivity K = 0.046 W/m oC. What is the rate of heat loss (in W) through an area 1.0 m wide by 1.5 m high, insulated with a layer of glass wool 20 cm (.2 m) thick, if the temperature difference across the layer is 20.0 oC...

Homework Statement There are 2 nichrome wires P and Q are connected in series to battery of emf , V . Both P and Q are of same length bu the diameter of wire P is bigger than that of wire Q . When wire P and Q glow steadily , which one would glow brighter ? Homework Equations The...

Homework Statement We consider the following configuration. A pile of N layers of sediments. Each layer has a conductivity \sigma_{i} (i from 1 to N) and a thickness m_{i}. The length of the system is L. In this case, the electrical conductivity is not a scalar but a second order symmetric...

Homework Statement A Cylindrical Tube of Length 35m, inner radius = 2.5m The tube is lines with 6cm thick insulation where k = 4X10^-5. The inside temp=25 degrees celcius Find the rate of heat delivered if the outside is -35 degrees celcius which keeps the inside temp at constant 25...

Why is the limiting conductivity of a weak electrolyte higher than the one for a strong electrolyte? ex: KCl = 149 Scm2/mol HAc = 391 Scm2/mol

Is the conductivity affected by the speed? Let's suppose that one linear conductor is going with c/2 speed which it's axis indicate the direction of speed. What will be the conductivity of this conductor in this case? The conductor will behave as an semiconductor? Marius

Homework Statement The passenger section of an airplane can be thought to have a shape of a cylindrical tube. For a small airplane, the tube is 35 m long and has an inner radius of 2.5 m. The exterior of the tubular wall is lined up with a 6- cm thick layer of insulating material of thermal...

Homework Statement The gap between a pair of parallel infinite copper plates extends from z = 0 to z = W > 0 and is originally occupied by vacuum (ε0, μ0). The plates carry equal and oppositely signed surface charge densities and as a consequence we have a constant electric field E = −4ˆz...

Homework Statement To summarize, I am given 6 objects and their corresponding specific heat capacity and thermal conductivity values. All objects have the same mass. The question is asking me to rank the objects based on temperature if they are put in a hot oven until they reach thermal...

Is it possible to calculate thermal conductivity of a material given just the delta-T at steady state and the material thickness? I have material that is 1/2 inches thick and has a 145 degree-C diffential @ 220C. Can I calculate its k-factor from that data alone? Thank you.

is there any corrolation between thermal conductivity coefficient and molecular wieght Mw according to the units [K] W/(m·K) it is independant of mass units (kg or g/mol etc) in my question i am asked to show with a graph, but i have no idea what graph they are talking about

I've stumbled upon a problem whilst doing my master thesis The problem is to construct the anisotropic conductivity tensor for a material that exhibits Anisotropic magnetoresistance. The problem has left me quite baffled, and coming to think of it, I've never seen a proper treatment of...

Homework Statement At what temperature does a carbon resistor have a resistance of 995 ohms, if it has a resistance of 1000 ohms at 20 degrees? What is its conductivity at the new temperature? Homework Equations The Attempt at a Solution I don't even know where to start.

Hello! I'm writing an essay on 'relationship between density and thermal conductivity'. Could anyone explain to me the relationship? e.g. is it proportional or reciprocal? I'm kind of closing to the answer by doing an experiment. I took two concrete blocks with different densities and got...

Hello! I'm writing an essay on 'relationship between density and thermal conductivity'. Could anyone explain to me the relationship? e.g. is it proportional or reciprocal? I'm kind of closing to the answer by doing an experiment. I took two concrete blocks with different densities and got...

Homework Statement The substance CoBr3 dot 4 NH3 dot 2 H2O ha a molar conductivity of 42 kS/m at infinite dilution. Indicate the composition of the coordination sphere. Homework Equations I don't know any relevant equations. The Attempt at a Solution Where can we read about how...

Homework Statement I am attempting to calculate the approximate time it takes for a stone slab to fully preheat, focusing only on one dimensional steady flow conduction. Both my area and mass are unknown. Thermal conductivity: 6.4 W/mK Specific heat capacity: 0.98 J/gK Density: 2,980...

Hi all In the following link it says: http://hyperphysics.phy-astr.gsu.edu/hbase/thermo/thercond.html "For metals, the thermal conductivity is quite high, and those metals which are the best electrical conductors are also the best thermal conductors. At a given temperature, the thermal and...

Homework Statement A chemist filled a burette with a solution of sulfuric acid. She then titrated it into a solution of barium hydroxide to a point where there was excess acid. If a conductivity set-up is placed in the beaker with the barium hodroxide at the start of the reaction, what will...

Hi, I am performiong electromosis into glass channels and I would like to reduce the silanol group conductivity. I am not an expert in surface treatment and I only know treatment with OTS but it makes the cannel become too hydrophobiac to use aquaeous solutions and that's hat I am using. Any...

Hi all I'd like to heat up a mile of buried copper cable to roughly 100 deg C. The centre core is 80mm dia solid copper with impregnated paper insulation. Maximum spot temp is 150 deg C. I can expose the core at each end and clamp on a heating element. I've got plenty of time =...

hello! I'm investigating on thermal conductivity of concrete blocks. I've got an equation for calculating K, which is Fourier's law. Q'=-k×A× ∆T/l I have to make the experiment simple as possible as i can. My plan is to heat one side of a block of concrete and measure the temperature difference...

I'm trying to get some sort of value for the electronic contribution to the thermal conductivity of copper. Most sources seem to give the total thermal conductivity K=400 \mathrm{W/(m\cdot K)} at room temperature. The electronic contribution should be given by the Wiedemann–Franz law...

Is iron electric conductor also when it's molten?

In the time between posting this and now, I have found my mistake. So, problem solved. Homework Statement Earth's lower atmosphere contains negative and positive ions, created by radioactive elements in the soil and cosmic rays from space. In a certain region, the atmospheric electric field...

Hi, I am doing an experiment involving activated carbon and I need to know if activated carbon has a high level of conductivity. I've searched the internet but without results. in addition, if the Active carbon can be made to be or is conductive, does the immense internal surface area still...

First question, is atomic packing factor as described in wiki the same as fill factor? If so, how does it relate to the conductivity? Does conductivity increase will the increase in atomic packing factor or fill factor? I don't understand the relationship between conductivity and fill...

This is not actual homework. I have not had any course in thermodynamics. I have completed Kinematics and Electrical physics courses at my university. My degree is related to Computer Science, not Engineering or Physics. I am asking if my solutions to these questions are relatively correct...

Hi all I want to convert thermal conductivity to thermal conductance. The problem is with the units. for thermal conductivity the units are [W/(m.K)] and for thermal conductance the units are [W/K] For E.g for copper thermal conductivity is 400[W/m.K] how can I convert it to thermal...

Help! Which has higher heat conductivity: water or air? And could you give me a proof as well? Regards, Quan Chi

Hi, I hope this is the right forum. I'm doing a school project on how to improve heat dissipation in heat sinks (water primarily) in computers. I've realized that I've taken a larger bite than I can chew, but my teacher wouldn't let me change so, I'll guess I'm stuck with making an honest...

Hi Everyone, I have a thousand data points that create a graph of Copper's Thermal Conductivity as it changes from a temperature of 4.5 K to 300K. These points create a somewhat bell-shaped curve, and I have been trying to find the equation to this curve so I can integrate it. I have...

Which statement explains that a water solution of hydrogen chloride, HCL, is an excellent conductor, while pure liquid hydrogen chloride does not conduct electricity? 1. Water is an electrolyte 2. Hydrogen Chloride ionizes in water 3. Hydrogen Chloride is a non-electrolyte 4...

a little guidance with thermal conductivity please... Homework Statement there isn't really a problem statement, as its a lab write up I'm doing. we had two blocks of the same metal, one at room temp and one at a fixed temp of almost 50 degrees. a Rod of different metal was put between...

can you please tell me, how do we measures the conductivity and dielectric constant of silicone oil and castor oil, because resistivity of silicone oil is very high so that's why it is difficult to mesure with conductivity meter,

Can someone explain to me the equation on complex conductivity found here : http://farside.ph.utexas.edu/teaching/jk1/lectures/node58.html" I am trying to understand why lightwaves penetrates salt water (conductor) but radiowaves can't.

Hi, I am not a Chem student but I have a few questions. I am looking for a non flammable chemical that is also conductive.Liquid form preferred! Multiple suggestions appreciated...

Homework Statement " Which of the following best describes a weak acid?" A. Its 0.10 M solution will have a pH = 1.00 B. It may be very soluble, but only partly ionized. C. It must be very soluble and completely ionized D. It must be of low solubility and completely ionizedHomework Equations...

can anyone explain the relationship between specific heat and thermal conductivity?

Hi, I'm working on my final year project for a part time mechanical engineering design degree course. I've built and tested a heat exchanger which is used for controlling the temperature of N2 gas. I'm currently working through the calculations so I can compare real against calculated values...