What is Resistivity: Definition and 199 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).
Hey I had a question on my quiz where it asked for the Resistance of aluminum at 600 deg C. But the formula rho-rho(i) = rho(i)a(T-T(i)) only finds the value of the resistivity at 600 deg C how do I convert it to resistance without more given info?
Question: A spool of aluminum wire has a...
Homework Statement
"A metal wire has a resistance of 10 ohms at a temperature of 20 degrees C. If the same wire has a resistance of 10.55 ohms at 90 degrees C, what is the resistance of this same wire when its temperature is -20 degrees C?"
Homework Equations
I am not exactly having...
Pls help me..thanks
Homework Statement
17. How long should a copper wire 20 mills in diameter be for it to have a resistance of 5.0Ω?
20. An electric motor draw 10 A from a 240-V source 120 ft away. What is the minimum diameter of the copper wire in mills if the voltage drop is not to...
Homework Statement
Two of the MHD equations can be formulated as
\vec{E} + \vec{v} \times \vec{B} = \eta \vec{J}
\nabla \times \vec{B} = \mu_0 \vec{J}
where [itex]\eta[/tex] is the resistivity of the plasma.
a.) Derive an equation for the magnetic field at very high resistivity and...
Hello guys.
My name is Luqman, and I am a new member of this forum. Currently studying in Japan on Metallic Glass/Glassy Metal/Metallic Alloy, which is a branch of solid state physics.
I have a million-dollar question though concerning metallic glass, which I would really appreciate if...
Homework Statement
i need to find the radius of a copper wire given the following data:
resistivity is 0.25 ohm meter
length of wire is 200 m
Homework Equations
roe=RS/I
roe=resistivity
R= resistance of material
S=cross sectional area
I= length of specimen
The Attempt at a...
Hey PFers,
So basically, we have these plates of bakelite that have on the order of 10^10 Ohms surface resistivity, but it is not uniform enough. Part of the reason may be that although these sheets may have some non-trivial non-uniform structure at a small enough scale.
These sheets of...
Hey PFers,
So basically, we have these plates of bakelite that have on the order of 10^10 Ohms surface resistivity, but it is not uniform enough. Part of the reason may be that although these sheets may have some non-trivial non-uniform structure at a small enough scale.
These sheets of...
In a problem it states that:
A 10.71 V battery is connected to a resistive strip that consists of three sections with the same cross-sectional areas but different conductivities.
In the solution to the problem it stipulates that the current density of the three sections are equal. Where in...
Homework Statement
A wire, 50.0 m long and 2.00 mm in diameter is connected to a source with a potential difference of 9.11 V, and the current is found to be 23.45 A. Assume a temperature of 20°C and using Table 17.1, identify the metal out of which the wire is made of.
Homework...
Homework Statement
(a) A sample of n-type Germanium contains 1023 ionized donors per cubic meter. Estimate the ratio at room temperature (300K) of the resistivity of this material to that of high purity intrinsic Germanium. The Electron hole product for Germanium is 1038m-6 and it can be...
See: http://img229.imageshack.us/img229/5353/cirlm2.th.jpg
L is varied by moving the crocodile clips along the wire.
Am I right in thinking that the current flowing will remain the same irrespective of the length?
My reasoning:
rho=AR/L
R=V/I
sub and rearrange to give:
I=AV/L(rho)
As L...
[SOLVED] Calculate resistivity of the material of the wire
Question:
0.75A Current flows through an iron wire when a battery of 1.5V us connected across its ends. The length of the wire is 5m and Area is 2.5 \times 10^{-7} m^2. Calculate resistivity of the material of the wire.
Equation:
R...
Homework Statement
I need to find the temperature coefficient of resistivity \alpha for silicon at the temperature of T=300 Kelvin. I am supposed to assume that \tau, the mean time between collisions of charge carriers, is independent of temperature.
Homework Equations
Temperature...
I read somewhere that the Hall conductance is proportional to the derivative of the density of states at the Fermi level, and somewhere else that the longitudinal resistivity is proportional to the density of states at the Fermi level. Does anyone happen to know which it is?
1. A wire with a resistance of 6ohms is drawn out through a die so that its new length is three times its original length. Find the resistance of the longer wire, assuming that the resistivity and density of the material are unchanged.
R = p (L/A)
Working out this problem I came across...
The resistivity arises because the electrons collide with atoms so they flow slower. The resistivity of different metals differ a lot. What determines the electrical resistivity of different metals? It is related to their structure? How?
Homework Statement
Here's the problem.
The resistance of a piece of constantan wire of radius 0.6mm is reduced to 1/3 its original resistance when a unifrom layer of copper is deposited on it. Find the thickness of the layer of copper
(Resistivity of constantan = 49*10^-8 ohm m...
Homework Statement
A toaster uses a Nichrome heating wire. When the toaster is turned on at 27 deg C, the initial current is 1.50A. A few seconds later, the toaster warms up and the current is now 1.30A. The avg. temp coefficient of resistivity for Nichrome wire is 4.5 x 10 ^ -4 (degree C) ^-1...
I have a piece of coursework due in soon (as a matter of fact, about 2 hours from now), and I need to know what the lmiting factors were. Here's the method:
(a copypasta from my handed-in plan)
For this experiment, I measured out a length of a resistive metal wire, and connected it to the...
Homework Statement
A sheet of aluminum is 1 um thick. A thick copper ring of radius b is placed on the film, and a (smaller) copper disk, of radius a, is placed on the film at the centre of the ring. The disk and ring are connected to the terminals of a battery, so that current I flows through...
Homework Statement
I'm supposed to estimate at what temp. copper will have the same resistivity as tungsten at 20 deg. C.
Homework Equations
The only equation I think is relevant is
p=p0[1+alpha(T-T0)]
The Attempt at a Solution
I know the resistivity of both copper and...
Homework Statement
A silicon sample is doped with 5.0 X 10^19 donor atoms/cm^3 and 5.0 X 10^19 acceptor atmos/cm^3
a)What is its resistivity?
b)Is this an insulator, conductor or semiconductor?
c)Is this intrinsic material?
Homework Equations
No clue.. this is where I need help
The...
Homework Statement
You have a 25 mm long cylindrical carbon resistor, with a cross-section of radius 15·10-6 m.
What is its resistance?
Homework Equations
Resistance = pL/A where p is the resistivity of the material, L is the length, and A is the area(?).
Also, given is that...
A coil of wire has a resistance of 37.800 Ω at 27.800 °C and 44.400 Ω at 56.000 °C. What is the temperature coefficient of resistivity? Do not enter units.
Equation: R=R0[1+α(T-T0)]
then i plugged in number to make the equation look like this:
44.400=37.800[1+X(56.000-27.800)]
and i...
For my coursework "Resistance in a Wire" I used the R=ρL/A formula to predict what resistance I should get. Yet, as it was a hot day:mad: when i did the experiment the Room Temperature was not ambient but 28°C. Therefore my there was a small systematic error with my results (they were...
A resistor is to have a constant resistance of 30(ohm), independent of temperature. For this, an aluminium resistor with resistance R1 at 0(celcius) is used in series with a carbon resistor with resistance R2 at 0(celcius). Evaluate R1 and R2, given that \alpha 1 is 3.9 x 10^-3 for aluminium and...
Im to do an experiment tomorrow, but I've no idea what kind of readings to take! I am going to be using a 100mA ammeter, to measure voltage and current. The current is to stay constant more or less but I am not sure what ranges of readings I am to take. Anyone help me please? :cry:
A potential difference V is applied to a wire of cross section A, length L, and resistivity p. You want to change the applied potential difference and stretch the wire so that the energy dissipation rate is multiplied by 35 and the current is multiplied by 3. What should be the new values of L...
While taking photographs in Death Valley on a day when the temperature is 51.0°C, Bill Hiker finds that a certain voltage applied to a copper wire produces a current of 1.000 A. Bill then travels to Antarctica and applies the same voltage to the same wire. What current does he register there if...
im doing a lab in physics where we measure the resistance of nichrome at different length intervals, when we plot the points and draw a line of best fit the line does NOT go through the origin, we are supposed to explain why but i have no idea why that is. can anyone help? thanks
I was thinking of parallel and series circuits and how they work, but then I began to think more about how I could apply that same knowledge to a wire in terms of resistivity.
I was thinking, well if you add another length piece on, that wouldn't increase electron flow.. that would make it...
Hey,
I'm doing a presentation on Kevlar, and was asked to state its properties and why it has those. I came across the fact that kevlar has a low flamability due to the high carbon:hydrogen ratio, I'm assuming that carbon doesn't burn whereas hydrogen does. Am i correct? Sorry it may be a bit...
OK doing some physics coursework at the moment where I have to measure the resistivity of Constantan. Anyway, for those who don't know, the resistivity of constantan is 49x10^-8.
Anyway the formula for those who don't know for resistivity is...
RA/l
So anyway at length of 100cm, with a...
Is the correct equation that relates to the electrical resistivity of a conducting material to its resistance:
p = RS/l
p = is the electrical resistivity
R = is the resistance of the material
S = is the cross-sectional area
l = is the length of the specimen
if I'm using the right...
:confused: oki, here's the deal, i have a 540W heating coil 110V nichrome wre 0.600mm in diameter. considering the variaion of resistivity with temperature, waht will the coil 4.2236 m actually deliver when it is heated to from 1200 C from 20 C. i have tried using R=R[o]*(1+alpha8(T-T[o]) and...
I calculated the resistance between two points (P and Q) on a sphere that are located on the two ends of a diameter by dividing the sphere into thin strips of thickness dz that are in series perpendicular to the line PQ (say the z-axis). I can get an expression for the indefinite integral in...
dear friends.. i am class 12 cbse students
we are supposed to do an investigatory project on resistance and resistivity
the project has been completed ...
but we need to have around 10 - 12 pages on relevant information on resistance..i wud be grateful if u cud hel p me collecting some...
Just wanted to see if anyone could check my work. I only have 1 opportunity to do this. Thanks yall!
1.) Suppose that you wish to fabricate a uniform wire out of 1.00g of copper. If the wire is to have a resistance of R=.5Ω and if all of the copper is to be used, what will be (a) the length...
Hi all,
I have two light bulbs, both for 230 volts. One has 100 watts, the other 15 watts.
It is clear that the 15W bulb has the higher resistivity. But is its filament
a) longer
b) thinner
c) both,
and why?
Thanks!
it all seemed pretty easy to start off with I've got all my results.
Voltage against current with a variable thing. but i can't do the equation, i have drawen up the graphs and followed the formulas but the results all come out wrong.
formulas: m=y/x m=volt/amp r=1/m which is the...
Ok, the coursework i have been give is on the Resistivity of conducting putty. I know that Resistivity is the relationship between resistance, length and cross sectional area.
But what do i do?
Do i just get different lengths and thicknesses of a metal and find the resistance...
please check my work someone.
A tungsten wire has a radius of .075mm and is heated from 20.0 to 1320 degrees C. The temperature coefficient of resistivity is 4.5x10^-3 (C)^-1. When 120V is applied across the ends of the hot wire, a current os 1.5A is produced. How long is the wire? Neglect...
So here is the problem
Two cylindrical rods, one copper and the other iron, are identical in lengths and cross-sectional areas. They are joined, end-to-end, to form one long rod. A 12-V battery is connected across the free ends of the copper-iron rod. What is the voltage between the ends of...
hi, i am doing my physics homework at the moment, and i have got stuck on the last part of a question. it is asking for the resistivity of the wire- the values i have are
length of wire 2.5m, cross sectional area 2.0mm squared, current of 3.0a flowing through driven by p.d. of 4.5V. the first...