Conduction Definition and 397 Threads

Homework Statement The door of an oven has a piece of glass of dimensions 20cm X 30 cm and thickness 0.50cm.when the interior of the oven is at temperature 200°C,determine the quantity of heat that flow through the glass in one hour.(for glass,K=0.80 Wm^-1K^-1) Homework Equations...

So, when I was learning about static electricity and induction and conduction, there were several labs done where a pith ball or electroscope could be manipulated through induction when a charged object was placed near it. In the case of the little pith ball, a negatively charged piece of PVC...

Hi, I am trying to work this problem out but I don't know how to solve the boundary value. here is the problem statement thanks in advance

Hello All, I have been trying to figure this out for quite some time now. Obviously, from a mechanical point of view, it is best to keep to keep the Playstation on a hard surface to ensure unrestricted air flow into the cooling intake vents. But, still remains, is a deeper question...

Homework Statement Hello! I am supposed to explain the behaviour of the thermal conductivity of tungsten. I have plotted the relation http://img340.imageshack.us/img340/9776/heatcond.jpg is also experimental data Temp[0 10 50 100 300 500 1000 2000 3400] and thermal conductivity...

Hello everyone, I don't understand how depolarisation jumps when axons are myelinated. Ok myelin is an insulator so in that section no current passes through. But how does that make the current jump, when current reached myelin wouldn't it be inhibited, why does it still travel. Also what do...

for metals the conduction and valence bands overlap. So how do you distinguish between the conduction and valence bands? How do you find out the lower limit of the conduction band and the higher limit of the valence band? Or is it the case that the highest conduction band in a metal goes from...

Homework Statement a) A slab of thickness L and constant thermal conductivity \lambda generates heat at a constant rate throughout of g W m–3. The heat is dissipated from both sides of the slab by convection into the ambient air at a temperature Tf with a heat transfer coefficient h. The...

Hello friends Fourier law of heat conduction states that: Q ~ A.(Dt/Dx) where A= area normal to direction of heat flow. Dt/Dx= temp gradient in same direction. Now, obviously rate of heat flow will depend upon temp gradient but my doubt is how/why...

As I understand it, thermodynamics indicates that heat will dissipate from hotter parts of a system to cooler parts. This is why, for example, it is impossible to harness latent heat to create energy if there is no heat-sink to move the heat from relative warmth to cold. What has me puzzled is...

Hi, I have a very basic question on formation of valance and conduction band. It is said that conduction band is above the valance band. So In a hypothetical lithium molecule formation(for example purpose) : If 100 Lithium atoms combine together, then 1S shell is split into 100 1S shells (one...

Homework Statement The base of the room in a house consists of wooden board which is 15 mm thick and of area 200 m^2. The thermal conductivity of the board is 0.15 W/m/K. The temperature of the room is maintained at 0 degree celcius and the base is at 20 degree celcius. If the owner now...

Hey guys, I was wondering about problem 12C.1 in Transport phenomena by Bird, Stewart and lightfoot. The problem states that a block of material initially at uniform T0 is suddenely exposed to T1 at all surfaces. Assume a solution of T=X(x,t)Y(y,t)Z(z,t) any help with...

Homework Statement An animal has a core body temperature of 37oC and a skin temperature of 34oC while in surrounding of an air temperature of 25oC. If the skin temperature fell, what would happen to: (i) the rate of heat transfer via conduction through body tissue? (ii) the rate of heat loss...

Homework Statement A mountain climber has a body surface of 1.80 m2 and wears fibrous clothing 1.00 X 10-2 m thick. He has a skin temperature of 33.1 ºC while the outer surface of his clothing is at 273.15 K. Calculate the total rate of conduction of heat through his clothing in Watts, (a)...

Homework Statement have band dispersion \epsilon = \epsilon_c + \frac{h^2 k_x^2}{2 m_x} + \frac{h^2 k_y^2}{2 m_y} + \frac{h^2 k_z^2}{2 m_z} Show density of states is g(\epsilon) = \frac{m^{3/2}}{\pi^2 h^2} \sqrt{2|\epsilon - \epsilon_c|} Homework Equations 2 \frac{d\vec{k}}{(2\pi)^3} =...

Homework Statement An aluminum wire with a diameter of 0.100 mm has a uniform electric field of 0.200 V/m imposed along its entire length. The temperature of the wire is 50.0 C. a) Determine resistivity b) Current density c) Total current d) Drift speed of the conduction electrons...

Homework Statement Estimate the mean drift velocity of a conduction electron in copper, assuming that there is one conduction electron per atom. Consider No. 14 wire (diamter 0.16 cm), common in houses, carrying 5A. The result should be very small. Why then does an electric light turn on...

Homework Statement If I have a cup filled with boiling water, where will heat loss by conduction and heat loss by convection occur? Homework Equations The Attempt at a Solution I think that heat loss out of the top of the cup (water in contact with air) will be convection, and...

Hi All, I'm trying to understand heat so I'm going to say what I understand and ask you to please tell me if I am correct. Thank you. Radiative Heat - This is heat transferred in the form of electromagnetic radiation and does not need a medium. If in a vacuum, the radiation will travel...

Dear all, I have difficulty in solving this problem (see the figure in attached thumbnails) I have a rectangular shape with length/height of L and the thickness/width of \delta Within the rectangular area, a heat conduction occurred. I would like to determine the temperature profile within the...

Homework Statement I need to set up the mathematical formulation of the following heat conduction scenarios: a) A slab in 0\le x \le L is initially at a temperature f(x). For times t>0 the boundary at x=o is kept insulated and the boundary at x=L dissipates heat by convection into the...

Homework Statement a bushwalker wears clothing that is 2.0cm thick with a surface area of 1.9m^2. The material has k = 0.042 WM^-1K^-1. Her skin temperature is 33 degrees C and the ambient temp. is 0 degrees C. Calculate rate of heat loss through her clothing while she is sitting...

Help! Heat Conduction into a gas! Hello All, I have a problem I've been trying to solve for some time and can't quite seem to figure it out. I need the help of some experts out there. I am no physics expert but I do have a basic understanding of math, algebra, and geometry. I am a beginner...

Hi all, I am working on the problem below, and I wrote the code, but it's not working. Can anyone help me out? And even any ideas on how to improve the code to make it more succinct? http://i25.tinypic.com/2v0zi8m.jpg Basically, it is a 2D conduction problem with convection heat...

Homework Statement conductivity=1/100 siemens/meter epsilon=3*epsilon[0] at which frequency displacement current is equal to conduction current? Homework Equations The conduction current is LaTeX Code: I =C * \\frac {dV}{dt} The displacement current D can be calculated from...

Homework Statement I need to go into this test with great aplomb. In each of Problems 1 through 8 find the steady-state solution of the heat conduction equation a2uxx=ut that satisfies the given boundary conditions. 1. u(0,t)=10, u(50,t)=40 ... 3. ux(0,t)=0, u(L,t)=0...

Homework Statement In each of Problems 1 through 8 find the steady-state solution of the heat conduction equation ∂2uxx=ut that satisfieds that given set of boundary problems. ... 3. ux(0,t)=0, u(L,t)=0 Homework Equations Assume u(x,t)=X(x)T(t) The Attempt at a...

Hello, I am trying to understand one-dimensional unsteady state heat conduction for a program I am writing. The program will eventually be coded for two and three dimensional structures. Can anyone provide some basic background info./tutorial to understand the governing equation and...

Homework Statement A conduction heat wave is caused to pass through a metal bar of average temperature Tmean = 35.0 °C, altering its temperature sinusoidally with an amplitude of Ti = 2.0 °C. The equation which gives the temperature, T(x,t), of the metal bar at any place x (in meters) inside...

Homework Statement The question - A small sphere (emissivity = 0.90, radius r1) is located at the center of a spherical asbestos shell (thickness=1.0cm, outer radius r2). The thickness of the shell is small compared to the inner and outer radii of the shell. The temperature of the small sphere...

Homework Statement a conduction coil with 2 resistors are connected, according to the drawing. write the expression for the potential difference Vac over the coil after t seconds after the switch is closed. Homework Equations The current at any time: (a) i=I(1-e-Rt/L) The electro motive...

Describe the physics behind an engineering system where heat conduction phenomena plays an important role. (a familiar system)

Homework Statement 1) I try to understand the lorentzian lineshape and relate to the gaussian graph but i don't know what is the difference. 2) Uncertainty principle- if it's related to the lorentzian lineshape it will give the information about the lifetime in the well and the width of...

Homework Statement A glass windowpane in a home is 0.62 cm thick and has dimensions of 1.0 m x 2.0 m. On a certain day, the indoor temperature is 25˚C and the outdoor temperature is 0˚C. a) What is the rate at which energy is transferred by heat through the glass? b) How much energy is lost...

Hi frnds... can anybody give me some idea about the"mechanism of balistic conduction." I really need it. pls help me.

Homework Statement A cubical box 22cm on a side is constructed from 1.3cm -thick concrete panels. A 100 W lightbulb is sealed inside the box. What is the air temperature inside the box when the light is on if the surrounding air temperature is 20 C? Homework Equations rate of heat transfer...

So this is my current problem: I have block of solid material that separates two bodies of gas. The temperature of all three is known (and presumably all different). The solid material is also being heated, equally throughout its volume. I want to know the instantaneous heat transfer...

I am an ME with my years of heat transfer approx. 20 years back. I have a 3' x 7' insulated sub floor that utilizes an electric heat mat (2' x 5'). The heat mat is on top of the sub floor. Oh and a reflective layer between the heat mat and the sub floor. Finally I have a .100" diamond plate on...

I need a fem code either in MATLAB or fortran to refer to as I am stuck at some places. Please help.

I'm not from the chemistry major but I need to learn solid state chemistry out of the need of my research. I viewed solid state chemistry lectures online delivered by professor Donald Sadoway from MIT. Particularly on the topic of conductors, insulators, semi-conductors, I have some confusions...

Homework Statement There's a radioactive isotope placed inside an iron sphere (R=2cm), which acts as a source of constant heat (P=1W). The isotope is uniformly distributed over a very thin spherical layer (r=1cm). How much higher is temperature in the center of the sphere compared to...

1. The problem statement A truncated cone 30cm high is made of Aluminum. The dia at the top is 7.5cm, and 12.5cm at the bottom. The lower surface is maintained at 93 deg C, the upper surface at 540 deg C. the other surface is insulated. Assuming 1 dimensional heat flow, calculate the rate of...

Find a general formula for the temperature u(x,t) in the form of a series with general formula for the coefficients of the series. \alpha^2 \frac{\partial^2 u}{\partial x^2} = \frac{\partial u}{\partial t} with 0 < x < L; t>0 u(0,t) = 0 \frac{\partial u}{\partial x} (L,t) = 0 with t>0...

Hello all, I'm trying to put as precise a finger as I can on the quantum-mechanical description of conduction so I could explain it to, say, a curious 8th grader. The goal here is not to be able to perform calculations but give an explanation that does not suffer the errors of the Drude model...

Homework Statement A steel cylinder of radius 7.0 cm and length 4.0 cm is placed in end-to-end thermal contact with a copper cylinder of the same dimensions. If the free ends of the two cylinders are maintained at constant temperatures of 85°C (steel) and 20°C (copper), how much heat will flow...

[b]1. Suppose the insulating qualities of the wall of a house come mainly from a 4.0-in. layer of brick and an R-19 layer of insulation. What is the total rate of heat loss through such a wall, if its total area is 195 ft^2 and the temperature difference across it is 15 degrees F. [b]2...

In the band theory it is said that, in conductors, conduction bands are only half-filled. So, when Electric filed is applied, the electrons can easiliy jump into higher energy states of the same band and move freely. If the electrons a so free to move, what constitute the resistance of the...

Homework Statement A tent being considered for cold-weather conditions has insulation on the top and sides with a conductivity, k = 0.040 W/(m*K) and a thickness, l = 0.50 cm. The tent (and surrounding medium) has the following conditions: a heater (inside the tent) producing heat at a rate...

Homework Statement Show that the equation governing the stead-state radial conduction of heat in a sphere or spherical shell with volumetric heat production is given by \frac{k}{r^2}\frac{d}{dr}(r^2\frac{dT}{dr})+\rho H = 0 where k is thermal conductivity, H is the heat production per unit...