Resistivity Definition and 200 Threads

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. 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. > -...
  2. minimario

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  3. jawad hussain

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    why resistivity of a metal increases with increase of temperature and conductivity of a semiconductor increases with increase in temperature??
  4. chikou24i

    Understanding Limit Current & Resistivity in Source Meter Machines

    We see always in source meter machines a LED which indicates the limit current. I want to know what is the limit current and what is the relationship between this later and the resistivity.
  5. S

    (Solid State) low resistivity dependance on temperature

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  6. S

    Resistivity mean free path and scattering time of copper

    so this is the question I'm having a little trouble with: Assume that the ratio of copper resistivity at room and absolute zero temperatures (so called "residual resistance ratio") is 1000. Estimate the electron mean free path in copper at low temperatures. we also know this: Let us assume...
  7. M

    Charge flowing through/across a Capacitor?

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  8. 1

    Estimating Resistivity of Amorphous Metal - Condensed Matter

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  9. S

    How can powder resistivity be measured with 4-point probe?

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  10. marcophys

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

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  11. J

    Why Is Length Divided by Area in the Resistivity Formula R=P*(L/A)?

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  12. Greg Bernhardt

    What is Resistivity? Definition & Equations

    Definition/Summary For a given material, the resistance of a length of the material is a constant times its length, and divided by its cross-section area. This constant is the resistivity, \rho, of the material. Resistivity of a material is measured in ohm-metres (\Omega m), or...
  13. S

    Regarding resistivity in heating coils

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  14. V

    Resistivity anti-helmholtz configuration

    If I have a pair of coils connected in an anti-helmholtz configuration, with current flowing oppositely in both, and I wanted to calculate the resistivity- wouldn't the length of both coils just be summed up? I tried this but I am not getting the answer I want.
  15. O

    NiCu Alloy Resistivity - Is it 3.5*10^8 or 35*10^8 Ω*m?

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  16. L

    Calculating Resistivity of Doped Si: P and As Substrate Comparison"

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  17. B

    Solving Resistivity Question: Determine Shunt Length

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  18. F

    What is the resistivity of a copper wire with given dimensions and length?

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  19. E

    How to Calculate Resistivity of a Non-Uniform Wire?

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  20. J

    Calculating Resistivity and Resistance: Solving for Unknowns

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  21. J

    Electrical resistivity tomography

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  22. J

    Resistivity in Archaeology: A Tool for Identifying Underground Objects?

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  23. F

    Resistivity of a material involving temp

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  24. B

    What Are the Units of Resistivity?

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  25. A

    Temperature dependence of the electrical resistivity of a metal

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  26. B

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  27. H

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  28. P

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  29. V

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  30. J

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  31. V

    Resistivity and Ohm's Law question

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  32. N

    Resistivity of conducting putty?

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  33. harts

    How to Calculate the Resistivity of a Rod?

    Homework Statement A uniform metallic rod, with a cross-sectional area of 1.83 cm2 and a length of 7.08 m, contains 6.24E28 conduction electrons per cubic meter of material, which have a mean collision time of 20.2 femtoseconds. (a) Determine the resistivity of the rod. When the rod...
  34. J

    How to calculate resistivity of coaxial cylinder

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  35. L

    Relationship between resistivity and Mathiessen's Rule

    This question has bogged me down for hours. Please help. An alloy of metals is found to have a resistivity of 1.2e-6Ωm at 300K. When it is heated to a temperature of 973K, the resistivity is found to increase by 10 per cent. Assuming Mathiessen's rule to hold good for the alloy, find its...
  36. V

    Electron-hole pair damping of vibration, thin film resistivity

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  37. E

    Question involving resistivity using the formula?

    Homework Statement The resistivity of nichrome wire is 1.1micro ohm meters. What length of wire of diameter 0.079 mm is required to provide resistance of 1.0 Kohm? Homework Equations R=resistivity x length/area The Attempt at a Solution 1000ohms = ? x 0.0011/0.079 79 = ? x...
  38. A

    Resistivity of Nichrome experiment

    Every year we do an experiment to find the resistivity of Nichrome wire, and every year the result is the same: 5 x 10^-7 instead of 1 x 10^-6. For the life of me I haven't been able to track down why it's a factor of 2 off. We use a Wheatstone bridge that has a 1 m length Nichrome wire...
  39. S

    How Does Resistivity Affect Copper Wire Resistance and Current Flow?

    12-gauge copper wire has a radius of 1.03×10−3 m. (a) What is the resistance of 11.5 m of this wire at 20°C. (b) How much current will pass through the wire if a potential difference of 9.00 V is applied across it? The resistivity for copper is 1.7E-8 ohm meters For part a: The equation is...
  40. K

    Bloch Theory of electrical resistivity - Derivation

    In "Electrons and Phonons" by Ziman which you can find here, I have a problem with equation (9.5.14) on page 360 and (9.5.17) on page 361. I don't understand how from the first equation where you have double surface integral you obtain the second equation with only one integral over q. I...
  41. K

    What does negative resistivity mean

    silicon has a negative temperature coefficient of resistivity. So that means that it's resistivity decreases as temperature increases. How is that possible? Also, would that mean that at some certain temperature higher than room temp, silicon would act as superconductor? It has a very high...
  42. Z

    Sources for resistivity of W depending on temperature

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  43. J

    A conducting wire has a resistivity

    Homework Statement A conducting wire has a resistivity, ρ as a function of its length, L, given by ρ=(ρ0)(L) where (ρ0) is constant. A is the cross-sectional area of the wire. the resistance of the wire would be A) [(ρ0)(L)]/A B) (ρ0)/(2A) C) [(ρ0)(L)]/(2A) D) [2(ρ0)(L^2)]/A E)...
  44. P

    How does the molecular bonding effect the resistivity of a material?

    Hello all, I want to understand the molecular structure for different electronic components: Conductors - need to have metallic bonding, where electrons are free to move about Dielectrics - are insulators, but ideally atoms need to be polarizable, without charge actually being able to...
  45. L

    Internal resistivity, is this right?

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  46. E

    Measuring Resistivity in a sample of A356

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  47. P

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  48. I

    The Effect of Temperature on Resistivity

    1) A thermistor is connected through a switch to a 12V power supply of negligible internal resistance. When the switch is closed, the initial current in the circuiy is 14mA. A few minutes later it has risen to a constant 20mA. Does the thermistor dissipate more power initially, or after it...
  49. I

    Help Easy Physics - Resistivity Ratios

    The resistivity of Aluminium is twice that of copper. However, the density of Aluminium is one-third that of Copper. a) For equal length and resistance, calculate the ratio: mass of aluminium/mass of copperI'm thinking, the density ratio (Al:Cu) is 1:3 ...and the resistivity ratio is 2:1 ...so...
  50. I

    Help with a current, resistance, and resistivity problem

    Homework Statement In the figure below, current is set up through a truncated right circular cone of resistivity 898 Ω·m, left radius a = 2.00 mm, right radius b = 2.30 mm, and length L = 1.64 cm. Assume that the current density is uniform across any cross section taken perpendicular to the...
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