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

    Electric plate has three sections with equal resistivity

    Electric plate has three sections with equal resistivity. Those resistivities combined parallel - water boils per 6 minutes. How much time it will take to boil the same weight and same initial temperature of the water if we will combine resistivities sections like in A and C Thanks very much
  2. Y

    Experiment to Determine the Resistivity of a Wire

    Here is a detailed description of my question: http://img829.imageshack.us/img829/3413/physics2.png" Any help would be greatly appreciated. P.S. Diameter of the wire = 0.425mm +/- 0.005mm .
  3. N

    How do we explain electrical resistivity and heat.

    I was looking in my old physics text in connection with another thread and the text said high speed electron collisions and slow speed drift of electrons with an applied electric field don't explain resistivity very well...yielding resistivities 100 times or more than observed. For a plain...
  4. S

    Meissner effect and conventional zero resistivity

    why shouldn't the meissner effect occur in a non conventional zero material?
  5. S

    Calculating resistivity from relaxation time.

    Given the following data on copper, how do i calculate the resistivity? Relaxation time: 2.50e10-14s Density: 8940Kgm-3 molar mass: 63.5g is there an equation for it.
  6. G

    What is the correct designation for resistivity and its unit for a copper wire?

    Hello to everyone. I am a little confused regarding what stands for the designation of [Ohm/m]. Before I used to [Ohm*m] for designation of resistivity (it calls sometimes resistance per unit length). For example I have a wire (copper). The resistivity could be found from the table (17.2...
  7. S

    Calculating Resistivity of Extrinsic Ge w/ Four Probe Method

    We have an experiment of the students to calculate the resistivity of an extrinsic (p or n) Germanium sample using Four Probe method at different temperatures (the sample is heated from room temperature and the voltage and current are measured for increasing temperature and then the same is done...
  8. S

    Calculating Resistivity: Finding the Area of a Wire

    Homework Statement A wire has a diameter of 1.51 mm and a length of 32.7 m, and is found to have a resistance of 1.5 capital omega. What is the resistivity of the wire? Homework Equations The Attempt at a Solution R=qL/A R=.0051/2=7.55E-4 L=32.7 A = ? How do i find A to...
  9. G

    What is the Definition of Resistivity and its Relationship to Resistance?

    I am revising for my A levels and I have noticed that a common question on the paper is to define RESISTIVITY. I have looked and looked but found no definitive description or a good definition. I know the formula but is it right to just say that "resistivity is directly proportional to a...
  10. sankalpmittal

    What is the difference between resistance and resistivity ?

    What is the difference between resistance and resistivity ?? I have studied that the electric resistance is directly proportional to length of material and inversely proportional to area of cross section . In this resistivity becomes constant and determines conductivity by sign "rho" . What is...
  11. C

    Relationship Between Resistivity and Conductor Dimensions

    Homework Statement A cylindrical conductor of length l, diameter D and resistivity ρ has resistance R. A different cylindrical conductor of resistivity 2ρ, length 2l and diameter 2D has a resistance A. 2R. B. R. C. R/2. D. R/4 Homework Equations I assume its R = pL/A The...
  12. T

    Resistivity of Ringer's solution

    Does anyone knows the resistivity of Ringer's solution?
  13. F

    Electron flow over a conducting surface of variable resistivity

    Hello fellow physics-people, I was just thinking about the following setup: We have a conducting surface (with smoothly varying resistivity) hooked up to some battery with the wires contacting the surface at two arbitrary points, A and B. How would we go about figuring out the current...
  14. D

    What is the relationship between heat loss and resistivity in a cable?

    Homework Statement http://img710.imageshack.us/i/2631001.jpg/ #29 Homework Equations p=I^2R P=IV The Attempt at a Solution well, the answer is D, but i don't see why the length matters? can anyone find out the equation for this problem? i thought it was B) cable B because it has...
  15. M

    Flow of electricity and resistivity (ohms law)

    I think what I am doing is pertaining to ohms law but I'm not sure because we're not suppose to rely on equations or literal physics terms, but when we learned from previous labs. So this is mostly conceptual and I want to make sure I'm thinking through this correctly. Diagram 1...
  16. M

    Ohm's law and resistivity, again

    Sorry everyone, I forgot to post my efforts in solving the problem, so here I go again: The question says: Suppose you wish to fabricate a uniform wire out of 1.00 g of copper. If the wire is to have a resistance of R=0.500 Ohm, and a density of d=8920 kg/m3, and if all the copper is to be...
  17. B

    Understanding Resistivity: Solving a Wire Material Mystery

    Homework Statement a 15ft length wire with a cross sectional area of 127 c mils has a resistivities of 8.74 ohms at 20 C. What material is wire made of. Any help would be appreciated. (pi/4*10^-6) was given by the book. Whats odd is when I enter pi/4*10^6 instead for wolfram I'm getting the...
  18. A

    Strange behavior of thermal expansion and resistivity equations

    The equation of linear thermal expansion is l=l_0\left[1 + \alpha(t - t_0)\right] (it is similar also to the equation of resistivity, \rho=\rho_0\left[1 + \alpha(t - t_0)\right]) \alpha is a constant dependent only on the material we are speaking about. Now, let's say I have a bar 100 m long...
  19. A

    Calculating Resistivity of a Cylinder with a Hole

    Homework Statement A cylinder of radius a with a hole through it (of radius a/2) is filled with a material of resistivity p_2. Show that the total resistivity is now 4*(pL / pi*a²) (p_2 / 3p_2 + p) Homework Equations R=pL/A The Attempt at a Solution I started with a full cylinder...
  20. R

    Zero Resistivity in superconductors

    What is the meaning of zero resistivity in superconductors? I mean, what's the cause of zero resistivity in superconductors?
  21. L

    How Do You Calculate Resistance and Current in a Carbon Block Using Ohm's Law?

    Homework Statement A block of carbon is 3cm long and has a square cross section whose sides are .5cm long. A potential difference of 8.4V maintained across its length. a)What is the resistance of the block? b)What is the current in this resistor? Homework Equations R=pL/A where p is...
  22. N

    Help with electrical resistivity equation

    Homework Statement I'm just trying to understand what the variables in this equation represent. This is part of a study of electrical resistivity lab that I am doing. I don't have my Kittel book with me, and the lab manual for some reason doesn't define these variables. Homework Equations...
  23. L

    Diameter of wire from voltage, length, resistivity

    1. A standard 100 W (120 V) lightbulb contains a 8.50 cm-long tungsten filament. The high-temperature resistivity of tungsten is 9.0*10^{ - 7} ohm*m. What is the diameter of the filament? 2. p= resistivity, E = V/L, I = AV/pL, R = pL/A... 3. I know that I'm going to solve for A =...
  24. J

    Understanding Resistivity and Current Relationships: Explained Simply"

    So, resistivity goes like \rho = R \frac{A}{l} (where A = cross sectional area, l = length) I solved for resistance and got R = \rho \frac{l}{A} If R = \rho \frac{l}{A} = \frac{V}{I} would the current correspond to the ampacity of the material? Or, if you were to replace R in the first...
  25. L

    Find the resistivity constant homework

    Homework Statement The conductance G of a device is defined to be the inverse of its resistance, G=1/R. What is the conductance of a device through which the current is 2 A when a potential difference of 60 V is applied? Homework Equations R= V/I R= (resistivity)X (length)/Area The...
  26. S

    Longitudinal resistivity in the Quantum Hall Effect

    My only problem with a basic conceptual understanding of the Quantum Hall Effect is the relation between longitudinal conductivity and resistivity when the magnetic field is such that the filling factor is an integer, and the Hall resistance is quantized. I fully understand the splitting of the...
  27. P

    Why is gold plated on high end audio equipment instead of using copper?

    Hi I was wondering why high end audio equipment is plated with gold when copper is obviously cheaper and has a lower resistivity. Anyone shed any light on this? Thanks Paul
  28. R

    How Is Maximum Resistivity Calculated from Intrinsic Resistivity in Silicon?

    Homework Statement Assume the mobility ratio u_n/u_p = b in Si is a constant independent of impurity concentration. Find the maximum resistivity \rho_m in terms of the intrinsic resistivity \rho_i. If b = 3 and the hole mobility of intrinsic Si is 450 cm^2/Vs calculate \rho_i and \rho_m...
  29. D

    How Does the Y-Intercept Help Calculate Resistivity in an L/R vs. L Graph?

    This is a suggested relationship between L/R and L L/R = kl + A/P P is the resistivity, A is the cross-sectional area and k is the constant for the circuit Using the value of the y-intercept find a value for P with the appropriate unit The graph of L/R against L had the intercept of...
  30. E

    Diameter of a wire with length, resistance and resistivity

    Homework Statement This question is about the heated front windscreen of a car The heater consists of resistance wires which are embedded in the glass A) The power of the heater needs to be 180W for a satisfactory demisting A car battery of Negligable internal resistance supplies 12V to...
  31. H

    Diferences b/w emf & voltage,Resistance & resistivity

    hi I am new member of this forum..Plz tell me how to use this forum & how to ask Question from other members...Plz tell me differences b/w emf & voltage,Resistance & resistivity..
  32. T

    Solve Gold Ring Resistivity Question, Practical Difficulties

    I was doing some questions from a book on resistivity and I came across this, I really can't work this out, I'm stumped.
  33. A

    What Is the Resistivity of Pure Steam?

    I am working on a Project that involves determination of Quality of Steam. In that I have few queries, so please help if possible: 1. Is there any mathematical relationship between Resistivity of water and temperature? because i am not able to find one, but since i am working on this...
  34. Y

    Explaining electrical resistivity behaviour from phonon perspective

    Hello everyone. This question may sound naive, but since I am relatively new to the subject, I would like to ask for some clarification related to phonon and electrical resistivity. As most of you might be aware of, electrical resistivity of crystalline metals increases due to increase in...
  35. N

    Thermal Resistivity: Is Zero Equal to Infinity?

    Hi all Is zero thermal resistivity equal to having infinite thermal conductivity?
  36. M

    Pure carbon and graphite have the same resistivity?

    I am just wondering if pure carbon and graphite have the same resistivity? Resistivity for pure carbon = 3.5 x 10^-3Ωm:frown:
  37. S

    Difference between Resistance and resistivity

    What is the difference between these 2 quantities? from my textbook defines resistivity as a specific property of a material and is = E/J where the resistance is the resistivity over a unit length and area. So I suppose the resistance is a measures of resistivity over a volume...
  38. E

    Why Does CuNi Have Decreasing Resistivity with Increasing Temperature?

    I've been googling around but i seems not able to find why CuNi have decreasing resistivity when temperature is increased at the range of 20 celcius - 80 celcius. Please enlighten me! thanks a bunch!
  39. S

    Electrical resistivity methodology

    Homework Statement anyone can give me the methodology to do the lab test about the electrical resistivity, porosity, saturation index and salinity of soil Homework Equations The Attempt at a Solution
  40. S

    What Is the Resistance of Each Wire in a Series Circuit at Constant Temperature?

    A carbon wire and a Nichrome wire are connected one after the other. If the combination has total resistance of 10.0 k ohm at 20°C, what is the resistance of each wire at 20°C so that the resistance of the combination does not change with temperature?(resistivity at 20°C of: nichrome= 1.5x10^-6...
  41. K

    Quantum mechanical resistivity

    Q: What is the quantum mechanical expression for resistivity of Plasma?
  42. C

    Resistivity and Resistance in n-type and p-type Germanium

    Resistivity of Ge I'm doing this lab and haven't taken any SS physics so I'm expected to pick up some of the theory on my own. I am having trouble explaining the resistance vs temperature curve for n-type and p-type Germanium, i.e. why does resistance increase and then drop from around 290 K...
  43. A

    How Does Frequency Affect the Resistivity of Silver as a Plasma?

    Homework Statement Considering silver as a plasma, I have taken the equation of motion for electrons in an electric field and found the resistivity to be \sigma_{N}=\frac{Ne^{2}}{m_{e}(i\omega + \tau^{-1})} The first part of the questions asks me to calculate the scattering time \tau at low...
  44. C

    Coursework - Determining Resistivity

    Hi guys, I am trying to work out ρ in an experiment. Ive got down to ρ/AxV = 6.4 I know V = 2 and A=0.0907mm, but it should be m. If i then work it out i get a stupidly small answer. Anyone help me out. Its like 0.0016096
  45. S

    Resistivity of a stretched wire VS unstretched state

    1. A wire of a 6.0\Omega resistance is stretched to three times its original length. Assume the diameter and resistivity have stayed the same, what is its new resistance? 2. R=\stackrel{\rho L}{A} 3. Since the only thing that's changed in the equation is L, having tripled, I was...
  46. N

    Circuits - Power and Resistivity

    Homework Statement A 530 W heating coil designed to operate from 110 V is made of Nichrome wire 0.500 mm in diameter. (a) Assuming that the resistivity of the Nichrome remains constant at its 20.0°C value, find the length of wire used. (b) If the diameter of the wire were doubled...
  47. S

    Resistance and Resistivity problem

    Homework Statement A piece of Nichrome wire has a radius of 8.6 x 10^-3 m. It is used in a laboratory to make a heater that dissipates 575 W of power when connected to a voltage source of 120 V. Ignoring the effect of temperature on resistance, estimate the necessary length of wire...
  48. C

    A Level Coursework - Resistivity

    Hi guys, I am currently in my AS year and a piece of coursework on resistivity of metals, how you derive the equation. But for the coursework i have to write an abstract on it, linking my experiment to a case study, does anyone have any good websites or information to help me out. This is...
  49. K

    How Can You Create a Temperature-Independent Resistor Combination?

    HELP!A problem on resistivity Homework Statement For some application it is important that the value of a resistance not change with temperature. For example, suppose you made a 3.70 KΩ resistor from a carbon resistor and a Nichrome wire-wound resistor connected together so the total...
  50. R

    Resistivity of tungsten filament

    ]1. A 1.3 cm length of tungsten filament in a small lightbulb has a resistance of 0.032 ohms. Find its diameter. Given: Length= 1.3 cm= .013m R= 0.032 ohms resistivity= 5.6e-8 ohms*meter [b]2. A= pi (r^2) R= resistivity (Length/ Area) The Attempt at a Solution R= resistivity...
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