Resistivity Definition and 189 Threads

Hello dear. I'm a graduate student specializing in Electronic Engineering. This is my first question on this forum and I hope to get some advices in here. I currently faced some challenges about DFT calculation. My study is to analyze the low dimensional properties of metals. And I try to...

I'm really not sure. Obviously I can get the units right with Resistance * thickness, but I assume there's a correction factor here that I can't find anywhere?

I recently conducted a physics lab to measure the surface resistivity of a conductive sheet of a paper with a carbon filler. The theoretical Rs is approx. 5,000 Ω/☐ for this paper and yet we have calculated two Rs values: Rs when Varying Length and holding Width = 10100 +/- 83.07 Ω/☐ Rs when...

Why is resistivity inversely proportional to resistance for NTC semiconductors?

Lets suppose a half ring whit internal radius a and external radius b and height t. We can calculate the resistance of the half ring considering that it is made of a number of parallel resistors each one with resistance given by: R = ρ L/S where L = π·r and S = t·dr. The resistance of each...

Divide volts by current to get resistance which is 8. Multiply both sides by 8 and sigma to get: $$\frac{1m}{8\Omega\times10^{-4}m^2} = 1250$$ But this answer seems to be way off. How did I go wrong? Thanks

What is the electrical resistivity of Caesium vapor? What is the electrical resistivity of Potassium vapor? Sorry there are no support material or reference links for this. Just a question. The unit must be in Ohm-meter.

I read that resistivity is related to the mean free path of electrons inside the material and on density of charged within it. The electric field does work to flow electrons through a resistor, and the energy is converted into heat due to collision with lattice ion, right? ( in free space they...

i really have tried all the formulas out there and can't seem to get a solid answer

Using the related equations, I have come up with an equation that I think would answer this question (#4). However, I was just wondering does the 'L' from equation #1 and 'l' in equation #3 cancels each other out when the substitution is made to give out equation #4 (since they are both the...

I explained what I want to tell you in the picture I add. Thanks in advance.

1. Would k be p/π? (since resistivity of a material is a constant property and π is a constant) I understand that typically R = pL/A Therefore, would the equation be R = k(x/(d/2^2)) Confessedly, I truly am baffled.2. R total = sum of individual resistors (in series) R total = R1 + R2+R3...+Rn...

Hi. Since, I can find conductivity by taking the reciprocal of resistivity, in this case, 1/0.455 Hence, I will end up with: ##\frac{1}{0.455}=C(300)^{-3/2}e^{(\frac{-0.67}{2(1.38*10^{-23})(300)})}## However, my C value seems to be invalid in this case. May I know what may went wrong here? Thanks

Referencing: http://www.vlsiinterviewquestions.org/2012/07/21/inverted-temperature-dependence/ Mobility decreases in a MOSFET with increasing temperature However, referencing: https://www.quora.com/Why-does-resistivity-of-semiconductors-decrease-with-increase-in-temperature Resistivity...

L=Ra/P =6x0.0006/5x10^-8 =72000

In the situation of a magnet moving towards a flat sheet of copper; why doesn't the copper gain angular moment as the electrons move in concetric circles? The electrons are experiencing friction as they move through the copper.

I calculated FS Model using Mathcad and I got that this part increases with decreasing width $\w$. This make the resistivity increases with decreasing width $\w$. This contradict the result of this model. Has anyone ever come across with this before? the original paper...

(Oh my god, why can't my post show normally? Some sentences just disappear, but I can still see them while editing. It's very weird. Can someone help me? I've reported.)I know only partially filled bands result in current density, and I think there must be not only 2 partially filled bands, but...

Homework Statement Homework Equations ##ρ=\frac{RA}{L}## ##I=\frac{ΔQ}{Δt}## ##I=\frac{ΔV}{R}## The Attempt at a Solution (a) ##ρ=\frac{RA}{L}## ##L=\frac{2*π*r}{2} = πr## ρ = (5*2.5*10-7)/(π*0.1) ρ = 4*10-6 Ωm. (b) Req = 7+5 = 12Ω ##I=\frac{ΔV}{R}## I = 36/12 = 3 A ##I=\frac{ΔQ}{Δt}## 3 =...

How did H.K.Onnes measure temperature and resistivity? As you know, Onnes is a dutch physicist that was the first person to liquefy helium and discover superconductivity a year or so later. I am wondering - what equipment was he using at that time? I couldn't find this information anywhere...

Hello and thanks for looking at this question. I have a semi-conducting sample which has been run on a PPMS system - measuring it's resistivity as a function of temperature. I switched to AC transport mode in order to measure the resistivity again while applying frequencies between 1Hz -...

In approximations for the applicability of ideal MHD to plasmas, it states that plasmas are considered highly collisional to permit the assumption that the plasma (i.e. electrons) follow a Maxwellian velocity distribution. Although is not resistivity based on collisions in the plasma? If there...

Homework Statement Hi guys, I'm currently writing an extended essay in Physics looking at the effect of percentage composition of Sn has on the electrical resistivity of SnPb Solder. I've noticed that Sn is listed as being a better conductor than Pb, despite trends of periodicity and have been...

Homework Statement A 60-cm long gold wire is soldered to a silver wire of the same length as shown in the diagram. If each wire is 2.00 mm in diameter, determine the equivalent resistance of the combination between A and B. Diagram is attached. Homework Equations R = ρL/A The Attempt at a...

Homework Statement Homework Equations R= pl/A effective resistance= 1/R The Attempt at a Solution I'm honestly don't know where to start, althought I know i need to do something with the 200 coils first, but I have no idea what should be done with it

I have studied the integer quantum hall effect mainly from David Tong's notes and i understand how the ## \rho_{xy}## is quantized in terms of the chern number. What I don't understand is - how the chern numbers relate to the number of filled Landau levels though. - I also don't understand the...

Hi all, I'm doing a little project about the wear of materials for tools for cutting machines.Yesterday, I was reading wikipedia page about electrical resistivity and I thought if it might be possible to evaluate the estimate the material loss of the tool through the measure of electrical...

Homework Statement We were given five samples of nichrome wire, each with a different diameter but the same length. A micrometer was used to measure the diameters. We then measured and recorded the electrical resistance, R in Ohms of each nichrome sample with a DMM. I will try to summarize all...

Homework Statement For what electric field strength would the current in a 2.0-mm-diameter nichrome wire be the same as the current in a 1.0-mm-diameter gold wire in which the electric field strength is 0.0095 N/C? dn = .002m dg = .001m Eg = .0095 N/C ρn = 100 * 10-8 Ωm ρg = 2.44 * 10-8 Ωm...

Homework Statement Determine the resistance of wire at room temperature and at the melting point of the given material. GIVEN: Material = Aluminum Diameter of wire ##= 0.5 mm = 5.0 * 10^{-4} m## Length of wire ## = 0.5 m = 5.0 * 10^{-1} m## Temperature Coefficient: ##\alpha = 3.9 *...

Homework Statement Initially, copper wire is 20oC then raises the temperature of the wire casing the resistivity up 12%, find the temperature at the final. Homework Equations R=Rref[1+α(T-Tref)] The Attempt at a Solution I am completely confused with this mathematics problem,Stucking with...

I started simply looking at a circuit breaker connection diagram, then I fell down the rabbit hole. So I wondered, if you had a piece of pure copper and getting rid of heat (structural integrity, gravity etc.) was not an issue, just how much current could you push through it before it hit it's...

I am depositing VO2 thin films on quartz and aluminum substrates and I need to find out whether the choice of substrate can effect the resistivity of the VO2 film. I know resistivity is a function of temperature but am not sure if it is effected by substrate choice. Any thoughts?

I'm trying to calculate the possible resistance of a graphite sheet that I'm using to coat surfaces of metal conductors, protecting them from wear, welding, and other possible failures. I can't seem to find an accurate value for the Resistivity, some sites state it's 7.8E-06, while others 3 to...

Hello there, Id like to estimate how the resistivity due to electron 'collision' with 1st Brillouin zone changes as a function of number of valence electrons in a metal. Say you start with Na, then add some other material with 2 valence electrons instead of 1, then the fermi wavevector will...

forgive me if this is too chemistry. I am playing around with pencils, writing and art pencils, to teach some kids about resistance and resistivity in a fun way, or so I believe. I get about 200 Ohms for a standard full length HB (whatever that means) pencil. I have some charcoal art pencils...

Hi everyone, I am looking for basic elements resistivity vs. temperature laboratory measurements charts. Anyone has ideas where to look for? Regards

I have voltage, diameter, area, and inverse area data values. How could I calculate the resistance and resistivity with these numbers? I am pretty sure resistance is R=V/I and resistivity= RA/L , so I am not sure how I can calculate resistance without an I value.

Suppose a wire made from an unknown alloy and having a temperature of 20.0°C carries a current of 0.529 A. At 52.4°C the current is 0.378 A for the same potential difference. Find the temperature coefficient of resistivity of the alloy. tempinital = 20C tempfinal = 52.4C currentInital = .529A...

Hi everyone! I'm trying to figure out how to go about this in calculating resistivity of a titanium grade 1 mesh. From what I know the ρ for titanium is 4.3x10^-8 ohm x m. The mesh will be a 1x12inch sheet wrapped cylindrically end to end. Here are the stock values including a change in area...

Homework Statement After performing a lab experiment to determine the conductivity if Pasco conductivity paper, I found the conductivity to be 0.195 Ωm. We found conductivity by graphing measured values of voltage (y axis) and the length (x axis) between the probes of a voltmeter that are...

Hi! I am currently trying to determine how the salinity ##S## of a sample of seawater (or, objectively, a salt-water solution) changes its electrical conductivity ##\sigma##. It is clear that they are proportional since the mobility of the ##\text{Na}^{+}## and ##\text{Cl}^{-}## ions plays a...

Why is the divergence of electric field not zero for a material with non-constant conductivity?

Homework Statement It is known that the theoretical resistivity of copper is approximately: 2*10^-8 Ωm. But after I conducted an experiment to find the resistivity of copper, the results turned out to be: 1.68*10^-8Ωm. This is a very small error that can be easily dismissed due to "human...

I'm not sure if corrosion does have a significant effect on copper in general but if it does, how and why does it happen, and the process of it happening and its effect on the overall resistivity? This is for a physics assignment...Please help if you can. Thank you

I'm having trouble understanding why the resistivity behaves as it does in comparison to the density of states for the quantum hall effect. Take the following two diagrams: (A) (B) I understand that there can be no scattering in (A) because all states are full (i.e. no elastic) and the gap is...

Today while reading a book i read that conductance of a metal depends on its density. But it is also dependent on its resistivity. Does that mean that resistivity and conductivity are proportional to each other?

>Two wires of the same material are both connected to a 9-V ideal battery. They have the same cross section area but wire 2 is twice longer than wire 1. Compare the following quantities by answering if the quantity for wire 1 is smaller, equal or greater than the same quantity in wire 2. > -...

Homework Statement ti[/B] A resistance thermometer, which measures temperature by measuring the change in resistance of a conductor, is made of platinum and has a resistance of 50.0 Ohms? at 20.0°C. (a) When the device is immersed in a vessel containing melting indium, its resistance increases...

why resistivity of a metal increases with increase of temperature and conductivity of a semiconductor increases with increase in temperature??