resistivity Definition and Topics - 26 Discussions

Electrical resistivity (also called specific electrical resistance or volume resistivity) is a fundamental property of a material that measures how strongly it resists electric current. Its inverse, called electrical conductivity, quantifies how well a material conducts electricity. A low resistivity indicates a material that readily allows electric current. Resistivity is commonly represented by the Greek letter ρ (rho). The SI unit of electrical resistivity is the ohm-meter (Ω⋅m). For example, if a 1 m solid cube of material has sheet contacts on two opposite faces, and the resistance between these contacts is 1 Ω, then the resistivity of the material is 1 Ω⋅m.
Electrical conductivity or specific conductance is the reciprocal of electrical resistivity. It represents a material's ability to conduct electric current. It is commonly signified by the Greek letter σ (sigma), but κ (kappa) (especially in electrical engineering) and γ (gamma) are sometimes used. The SI unit of electrical conductivity is siemens per metre (S/m).

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  1. E

    Finding a radius of a wire

    i really have tried all the formulas out there and cant seem to get a solid answer
  2. Y0SHI0N

    Can two variables in two different equations cancel each other?

    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...
  3. R

    Please check my calculation of the resistance of this wire shape

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

    I Fuchs-Sondheimer Resistivity model for Nanowires

    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...
  5. Philethan

    A Why do we need to know "two-bands" Hall coefficient and magn

    (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...
  6. Dr Eve Wildman

    A AC transport data query (using a PPMS system)

    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 -...
  7. S

    Why is Sn a better conductor than Pb?

    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...
  8. Z

    Resistance of 2 materials, different resistivity, combined

    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...
  9. M

    Lab: Plot graph of resistance, R (in Ohms) versus 1/d^2

    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...
  10. ricky25j

    Electric field in a wire with same current as another wire

    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...
  11. E

    Resistance of a Wire at varying temperatures

    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 *...
  12. Pao44445

    Resistivity and Temperature

    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...
  13. T

    Maximum current carrying capacity (theoretically infinite?)

    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...
  14. J

    B Resistivity tensor and Magnetoresistance

    Hey everyone, I'm currently trying to understand the resistivity and conductivity tensor of a 2D sample. If a current carrying metal bar is placed inside a magnetic field the Hall Effect comes in to play. I tried to search for explanations on how to obtain the resistivity tensor of the metal...
  15. V

    Theoretical vs measured sheet resistance of conductivity paper

    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...
  16. R

    How dopant enhances the superconductivity of BSCCO

    Good day! i really need your help, I want to know the effect of Dopant (for Example Manganese) in BSCCO (for example Bi-2212) on it's Resistivity? i read some articles saying it increases the critical temperature of the superconductor, But it didn't explain why, and how is that related to the...
  17. H Smith 94

    Electrical conductivity of seawater depends on salinity how?

    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...
  18. fricke

    Divergence of electric field

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

    Need help in determining a source of error in an experiment

    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...
  20. P

    How does corrosion affect the resistivity of copper wire?

    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
  21. Rushikesh Sarda

    Are density and resistivity proportional?

    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?
  22. A

    Length of Wire Effect on Current and Inner Electric Field.

    >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. > -...
  23. minimario

    Temperature Variance with Resistivity

    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...
  24. M

    Charge flowing through/across a Capacitor?

    Homework Statement Dry air has a resistivity of about 3*10^13 Ωm. A capacitor has square plates 10cm on a side separated by 1.2mm of dry air. The capacitor is charged to 250V. Assuming the potential difference does not change as the charge flows, what fraction of the charge will flow across the...
  25. 1

    Estimating Resistivity of Amorphous Metal - Condensed Matter

    Homework Statement Estimate the resistivity of an amorphous metal whose mean free path is of the order of an atomic spacing. Compare your answer to crystalline copper. Homework Equations VF = h(bar) KF / m VF = l / τ ρ = m / n e2 τ The Attempt at a Solution I think my real issue with this...
  26. marcophys

    HT 'low current' resistance fundamentals in Tungsten Welder - event horizon

    Does anybody understand the fundamentals of what is happening in this circuit? Tungsten welding info is all about high current..... but this is a low current scenario. AC input, CDI Coil generated 20Kv (estimated) suffers voltage drop over 100mm of tungsten rod. The larger the diameter...