What is Thermal conductivity: Definition and 185 Discussions
The thermal conductivity of a material is a measure of its ability to conduct heat. It is commonly denoted by
k
{\displaystyle k}
,
λ
{\displaystyle \lambda }
, or
κ
{\displaystyle \kappa }
.
Heat transfer occurs at a lower rate in materials of low thermal conductivity than in materials of high thermal conductivity. For instance, metals typically have high thermal conductivity and are very efficient at conducting heat, while the opposite is true for insulating materials like Styrofoam. Correspondingly, materials of high thermal conductivity are widely used in heat sink applications, and materials of low thermal conductivity are used as thermal insulation. The reciprocal of thermal conductivity is called thermal resistivity.
The defining equation for thermal conductivity is
q
=
−
k
∇
T
{\displaystyle \mathbf {q} =-k\nabla T}
, where
q
{\displaystyle \mathbf {q} }
is the heat flux,
k
{\displaystyle k}
is the thermal conductivity, and
∇
T
{\displaystyle \nabla T}
is the temperature gradient. This is known as Fourier's Law for heat conduction. Although commonly expressed as a scalar, the most general form of thermal conductivity is a second-rank tensor. However, the tensorial description only becomes necessary in materials which are anisotropic.
TL;DR Summary: Trying to understand why there might be errors when using certain materials in a physics lab and how aluminum foil might impact this.
I am looking for assistance on answer these questions.
1) What would likely be a significant source of error in performing this experiment on...
Whats its thermal conductivity compared to copper? (as in x times worse than copper)
also, How electrically insulate is it? I'm looking to see if i can use it to encase an entire motherboard in a giant heat sink for a future project where i want to try and cool the entire motherboard to subzero...
I know k is thermal conductivity but my teacher never told me about effective coefficient of thermal conductivity. I tried googling and found:
$$k_{effective}=\frac{\Sigma{k.A}}{\Sigma A}$$
But I don't know the area to used that information. Is there another approach to do this question?
Thanks
I've tried to explicitly solve the Fourier's equation in cylindrical coordinates but I'm getting some messy integrals which cannot be solved analytically. Additionally my instructor said that there's a neat trick for this problem and it's possible to obtain the answer in a rather elementary...
Good afternoon everyone!
I've learned that thermal conductivity has a form of second-rank tensor. As you know, diagonal components of stress tensor mean normal stress and other components mean shear stress and like that do off-diagonal components of thermal conductivity tensor have some special...
When we measure 'the rate of conduction heat transfer'=Q , we assume that the hot side and the cold side's area are same. But if the both side's area is different to each other, how can i know the rate of conduction heat transfer?
like below figure.
Would you like to help me?? Thanks.
We know that,
Conduction Heat Transfer Q = KA(t2-t1)/thickness
K is the coefficient of thermal conductivity. If T2 = 1020°C and T1= 22°C also consider we know A and thickness value.
K depends on temperature. K varies with temperature. For all the materials we have a tabular data of K for...
Hello,
I'm searching for how magnetic field affects the thermal conductivity of the metal (such as steel in solid form). If someone suggests any article about it will be very helpful.
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Overall thermal conductivity?
for example, there are 3 layers made of different materials, having different thermal conductivities bonded with each other;
conductivity of layer 1= k_1 = 1 W/m-K
thickness of layer 1= t_1 = 0.004 m
conductivity of layer 2= k_2 = 148 W/m-K
thickness of layer 2=...
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Homework Statement
Hello,
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Hello, my name is Stephen Lanford and I am currently working on a Physics II lab.
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Just a quick question if I have a let's say a heat source of under a layer of bricks that have a thermal conductivity of 1.6 (W/m/°C.) and on top of the brick a layer of copper with a thermal conductivity of 398 (W/m/°C.).
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Progress
This is the experimental data of thermal conductivity of stainless steel 304L at low temperature. The data is calculated with the Fourier's law of thermal conduction. I checked many times in the excel file and I confirmed that there is no mistake in the calculation. The parameters are...
Homework Statement
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I...
HI,
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Homework Statement
I must calculate chemical potential using the Boltzmann equation in relaxation time approximation $$f=f^0-\tau v_z^2 \partial f^0/\partial z,$$ where ##f^0## is given as
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Hi!
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Homework Statement
Homework Equations
P = k A \frac{dT}{dx}
The Attempt at a Solution
a)
Assuming steady state transfer, energy transfers through rods at the same rate everywhere.
Letting T be the temperature at the point of welding.
P_1 = k_1 A \frac{T_h-T}{L} \\ P_2 = k_2 A \frac{T -...
Hello Physics Forums!
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1. Homework Statement
I've been failing to find examples dealing with "longitudinal" thermal conductivity and how two objects in contact with each other would affect the heat flow compared to not being in contact at all.
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Homework Statement
The problem is given.
Homework EquationsThe Attempt at a Solution
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Hi Guys
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Homework Statement
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Homework Statement
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Homework Equations
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Also:
I believe that...
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Wood and Copper are heated upto a steady state condition which will have a higher average of temperature at points ?
Please state your mathematical approach
1. Homework Statement
Dimensions remain same for both the materials as well as the temperatures both are heated to is the same
Homework...
How to calculate K or Q without one or the other?
For example, if the material is unknown (but cannot test density, or melting temperature)
how would you test heat flux?
Q=K(Th-Tc)/(x)