Conductivity Definition and 382 Threads

Hi Not really sure where I should post this. I am devising an experiment to measure changes in sea water salinity in river estuaries due to tidal flow. Sea water has a standard resistance of approximately 0.2ohm.m. My samples will need to be considerably smaller than 1m^3, I was thinking...

Hello, My 10 year old is doing a science project in which he places a zinc nail and copper nail in a liquid, hooks each nail up to a voltmeter and then measures the recorded voltage for each substance. Liquids include lemon juice, distilled water and ammonia. The book from which he got the...

Some companies seem to be selling "smart glass" products that can be electrically tuned at will to be either mirroring or transparent, at least in visible wavelengths. Suppose someone were to Faraday shield a room to prevent van Eck phreaking or whatever kind of eavesdropping from outside...

Hi For a personal project, where can I find the free carrier density and the electron momentum relaxation time of various substances (i.e. Carbon etc .....). Is there a book or something ? Thanks. Adrian

I have no idea whether in V=IR, V can be standard reduction potential, and R is inverse electrical conduciveness of that metal. I plotted the reduction potentials and they are strongly inversely correlated with resistance. I'm more confused by this because I have no idea how much amperes "A" we...

I first thought of imaging techniques, because the setup reminded me of it, but i have only ever seen those of electrostatics. If i for example add a current in the opposite direction and with the opposite heigth of the surface the fields dont cancel out at the surface, i think. What is the best...

Hi, Can I get help ranking Copper, Brass and Bronze by Thermal Conductivity? This stuff below says Copper is the best Thermal Conductor, and Bronze is the worst. https://en.wikipedia.org/wiki/List_of_thermal_conductivities https://www.engineersedge.com/properties_of_metals.htm...

I have attached a PDF file.

TL;DR Summary: What would happen if a bolt of continuous lightning hit an enclosed saltwater space with someone swimming far below the surface? Hello! I'm actually asking this as a DM for a DnD campaign. One of my players trapped a bad guy within a large (30m/side) freestanding cube of...

I have trouble researching whether valence-electrons take part in electrical conductivity. Some sources say that a lower amount of valence electrons lead to an higher electrical conductivity, whilst others say the opposite. And each have their different reasons, for example, lower valence...

What'd be practical method and/or portable, simple tool (like sort of electricians' multimeter) to meter the heat conductive constant of a metal?

What is/are the electric conductive material(s) which has/have the least heat/thermal conductive?

I understand that electrical conductivity is a measure of how easily charges are able to move in an object. During charging by conduction (for conductors), it seems that we simply have to add the charges of both object together and divide by two to obtain the resultant charge of either object...

Whats its thermal conductivity compared to copper? (as in x times worse than copper) also, How electrically insulate is it? I'm looking to see if i can use it to encase an entire motherboard in a giant heat sink for a future project where i want to try and cool the entire motherboard to subzero...

One has two same volume blocks of metal, one Aluminium and one copper pushed together. If the Aluminium is instantly heated to 100 degrees C, since it has significantly higher heat conductivity will the copper draw the heat out and at some point be hotter then the aluminium? Or will it just draw...

Okay so this is how it looks like,and there are the given values; a) I've tried it like this. So I now this formula $$ E = \frac{J}{\sigma} $$ where sigma is the conductivity value. Now to get E we need this formula; $$ U = \int_{l}{} E \ ds ] $$ Now to get U we can use the ## U = \frac{P}{I}...

I would like to know if spider's web is conductive. A google search was inconclusive, some sites say that it is conductive, some that it has a high breakdown voltage. The reason I am asking this is that it seems that I got spiders in my room (honestly I don't know where they are coming from)...

I know k is thermal conductivity but my teacher never told me about effective coefficient of thermal conductivity. I tried googling and found: $$k_{effective}=\frac{\Sigma{k.A}}{\Sigma A}$$ But I don't know the area to used that information. Is there another approach to do this question? Thanks

I've tried to explicitly solve the Fourier's equation in cylindrical coordinates but I'm getting some messy integrals which cannot be solved analytically. Additionally my instructor said that there's a neat trick for this problem and it's possible to obtain the answer in a rather elementary...

Good afternoon everyone! I've learned that thermal conductivity has a form of second-rank tensor. As you know, diagonal components of stress tensor mean normal stress and other components mean shear stress and like that do off-diagonal components of thermal conductivity tensor have some special...

I have a question in regards to a neuromuscular device. Can silicone be combined with hydrogel or the rubber silicone encased in hydrogel to form a wrist watch strap combined with a NMES device. If this is possible how would the hydrogel conduct the NMES device and what is the durability of...

The intrinsic concentration ##n_i## varies with T as ##n_i^2 = A_0T^3e^{\frac{-E_{G0}} {kT}} ## ---> eq1 The mobility ##\mu## varies as ##T^{-m}## over a temperature range of 100 to 400K. For Germanium, m = 1.66 (2.33) for electrons (holes) as per book. The conductivity is given by ##\sigma =...

We are using the textbook by Jin, "Theory and Comutation of Electromagnetic Fields". In the section on metamaterialshe derives the dispersion relationship. He shows that when ε'= -ε & μ' = μ then the dispersion equation γ =\sqrt{jωμ( jωε +σ )} = α + jβ goes to γ = α = ω \sqrt{μ'ε'}...

We know that, Conduction Heat Transfer Q = KA(t2-t1)/thickness K is the coefficient of thermal conductivity. If T2 = 1020°C and T1= 22°C also consider we know A and thickness value. K depends on temperature. K varies with temperature. For all the materials we have a tabular data of K for...

Hello, I'm searching for how magnetic field affects the thermal conductivity of the metal (such as steel in solid form). If someone suggests any article about it will be very helpful.

Hi y'all, I think this is my first time in the chemistry section of this forum, so thank you in advance for your patience with what is (I'm pretty sure) an elementary question. I've googled around for this a bit, but my last acid chemistry study was in 2002 or so, so the reading I am doing is...

In my search, I have been looking for any data that might explain the RF resistance from 3 to 30 MHz range of the two basic types of copper oxides that form on the outside of bare copper wire. I believe these oxides become semiconductors and have large range of impedances. Due to the nature...

Here is the Q below I want to see if my values for part b) is okay? This is what I have tried: Any help would be nice! Thanks

Hallo guys,Im kinda confused about something and hope you can help me. Let me introduce you to it. we take a look on one Mechanismen to the spin hall effect, skew scattering effect. i just read that you can see this contribution only in the clean Limit. So that's really strange for me cause...

Summary:: What if you were calculating the voltage potential for a dipole, but underwater? I'm making a predictive model (in R programming) for the voltage potential at any point around a dipole. I need to be able to change parameters, one being the k constant. V=( kpcosѲ)/(r^2). Where V is...

I'm trying to find a heat transfer equation that includes time. Metal tank, partially filled with liquid. I need to find the time it would take for the temperature on the outside of the tank to drop from θ2 to θ1, given thickness, metal and liquid's properties, and tank dimensions

Overall thermal conductivity? for example, there are 3 layers made of different materials, having different thermal conductivities bonded with each other; conductivity of layer 1= k_1 = 1 W/m-K thickness of layer 1= t_1 = 0.004 m conductivity of layer 2= k_2 = 148 W/m-K thickness of layer 2=...

Hi, A question has arisen an a hifi forum (sorry) that cables can be directional. I dispute this, as the proposed mechanism is diodes in the crystal structure etc. or the drawing process to crate the strands. Assume that it is 99.9% pure copper (CW004A (was C101)) and forms part of a cable with...

I did search Wikipedia and other science related websites, couldn't find an answer. Let me know if anyone knows the story behind G.

Hi, I would like to know if there is some current conduction with hole in semi metal ? thank you

I worked on a lab experiment that was meant to measure heat capacity but left me with some other questions. The students measured the mass of a cup of liquid nitrogen as it boiled off, recording mass vs time. Then they drop a solid object into the bath, one experiment with a small bit iron...

Can the electron-electron interaction have an impact on the conductivity? Google seems to point out that yes for some 2d materials such as graphene. But what about 3d materials? Intuitively, any lost momentum by an electron would be gained by another electron, so in average, this e-e...

Hi When I read the following article: http://nopr.niscair.res.in/bitstream/123456789/14183/1/IJPAP%2050%286%29%20405-410.pdf I tried to convert the value of the conductivity for saline in 500 MHz. At the article, they present the conductivity as ε'' = 70. Which ε'' is the imaginary part of...

(i) Dividing the rod into thicknesses of dx we get discs of area A with lengths=dx so using (****) we have the resistance of a typical disc (between point x' and x'+dx) as: (1) ##R(x'dx)=\frac{dx}{g(x)A}## (ii) Using (1) and (*) and the integrating from a to b of the entire rod we get...

A) What are the modern techniques used for enhancing the thermal conductivity of Phase changing materials (PCM) ? B) what are the negative effects (disadvantages) of using old methods of enhancing thermal conductivity of PCM ? ( construct table ) C) what are the different techniques used for...

Hi, yesterday a professor of mine told me that if you have a temperature gradient along the x-axsis you could have heat flowing in the y direction. Mathematically it is pretty straightforward to find the thermal conductivity tensor required, but in real life can you name some materials that...

Suppose that a large mixture of ice and water is in thermal contact with a reservoir which contains a large quantity of water and steam. Assume that both the ice/water bath and the water/steam reservoirs are otherwise thermally isolated and at a constant temperature. The only contact between...

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...

Hello all, I would like to know which of the above two methods used in determining concentration of a solution is more accurate? Thanks, KV

I'm trying to go through chapter III of the vol.8 of Landau and Lifshitz series. (Fortunately the book is uploaded to the archive.org, I guess it is in the public domain.) At page 87 ( << Archive.org link deleted by the Mentors because of copyright violation >> ), they speak about the Joule...

Does chromium oxide reduce the effectiveness of a faraday cage constructed from stainless steel mesh? I am using mesh that is like insect screen for windows. It will be in moist environment. I appreciate your help!

Hello, my name is Stephen Lanford and I am currently working on a Physics II lab. I am solving for the thermal conductivity of four materials (glass, plexiglass, pine, and sheetrock) using data from thermal conductivity experiments. The experiments consist of a steam chamber at 100 C, a block...

The common mantra is that when measuring conductivity in solutions the electrodes will build up a polarization layer and disturb the measurement, thus a 4 electrode measurement is used and an alternating current impressed up on the outer electrodes, usually around 1000 hz. I have been trying to...

Hi, I have a curve, impedance magnitude vs frequency. i would like to convert this curve to electrical conductivity vs time. how can i do that?

Hello, Just a quick question if I have a let's say a heat source of under a layer of bricks that have a thermal conductivity of 1.6 (W/m/°C.) and on top of the brick a layer of copper with a thermal conductivity of 398 (W/m/°C.). Is my assumption right that since the layer of brick has such a...