Conduction Definition and 397 Threads

Homework Statement We approximate the effect f exchange interactions among the conduction electrons if we assume that electrons with parallel spins interacti with each other with energy -V, and V is positive, while electrons with antiparallel spins do not interact with each other. (a) Show...

Hi. Everyone I have stuck in the problem of 2D conduction problem by using matlab, here is the following question: Consider a long bar of square cross section (1.0 m to the side) and of thermal conductivity 2 W/m.K. Three of these sides are maintained at a uniform temperature of 300°C. The...

Homework Statement Desperate help needed on the derivation of the differential equation on conduction on a clyinder, i have come close to the answer and working with the co-ordinates scale of T(r,0,z). I am sure that i have made a simple mistake but am blind to it right now, i have...

Hello, Can someone please explain the difference between conduction and induction? Thank you, ~English10

Homework Statement Obtain the temperature distribution T(x,y) of the triangular cross section, assuming constant thermal conductivity, k. The triangle is a right-isosceles triangle with the right angle at (0,0). The triangle goes "up" to a, and to the right to a, then diagonally across...

The temperature in an electric oven is 165°C. The temperature at the outer surface in the kitchen is 55°C. The oven (surface area = 1.6 m2) is insulated with material that has a thickness of 0.023 m and a thermal conductivity of 0.045 J/(sm°C). a) How much energy is used to operate the oven...

Hi, I was wondering something. What is the mechanism of energy transport when electricity is conducted through a conductor? The continuity equation requires current to be constant in a circuit, which means the expectation velocity of the electrons in the conduction bands must be constant...

In the steady state heat conduction through a solid rod the theoretical derivation tells that heat in-heat out-heat accumulated =0. What is a practical steady state heat conduction problem? what is transient heat conduction

I am looking to calculate the energy gap of for starters periodic elements and were wondering how we could get the list and calculation. Is there a table somewhere based on certain temperatures and constants of energy gap level? We would like to get a list of the energy gap energy for valance...

I know how to solve a 1-D heat conduction equation when both ends are kept at 0 temperature(using separation of variables and Fourier series.). In the notes, the prof asked us to solve for one end kept at zero and the other insulated (at x=L) and referred to a non-existent chapter in our...

Homework Statement Find the amount of thermal energy that flows per day through a solid oak wall 10.0 cm thick, 3.00 m long, and 2.44 m high, if the temp of the inside wall is 21.1 C while the temp of the outside wall is -6.67 C. Homework Equations Q= k(A)(T2-T1)t/d coefficient of...

Homework Statement .005 m of Ice is in contact with .0015 m of Aluminum. The temp of the Ice is -10.0 degrees C, and the temp of the Aluminum is -25.0 degrees C. I need to calculate the heat per second per square meter that is conducted through the Ice - Aluminum combination Homework...

Homework Statement Two identical conduction spheres are placed with their centers 0.30m apart. One is given a charge of 12 x 10 ^-9 C, the other a charge of -18 x 10 ^-9 C a) Find the electrostatic force exerted on one sphere by the other. b) The spheres are connected by a conducting wire...

Homework Statement Calculate how many conduction electrons pass through a given area per second when a current of 1A flows. Homework Equations Current density, j = i/A (i=current, A=cross sectional area) Current desntiy, j = nev[SIZE="1"]D (n=no of electrons per unit volume...

Homework Statement The elements of a boiling water nuclear reactor consist of long cylindrical rods of uranium dioxide (U02) of diameter 8mm surrounded by a thin layer of aluminium cladding. In the reactor core the elements are cooled by boiling water at 285°C with a heat transfer...

why are some materials better conductors/insulators than others? it'll helped if explained at the atomic level thanks

Homework Statement elephants have large ears because they need additional skin to balance the large amount of mass (to balance the heat eleminated from their skin with the heat generated by their body mass) by which methods of heat transfer do the ears eliminate excess body heat...

The temperature in an electric oven is 160 °C. The temperature at the outer surface in the kitchen is 38.6 °C. The oven (surface area = 1.44 m2) is insulated with material that has a thickness of 0.0249 m and a thermal conductivity of 0.0405 J/(s m C°). (a) How much energy is used to operate the...

Ok for example, if a solid conduction sphere was charged to 500volts and had radius of 1cm. Then charge, Q = VR = 5? So the E field just outside the sphere would be E = (1/4pi epsilon) x charge/R^2 = 4.5 x 10^14? Or am i getting confused?

Hi all, From Pauli's principles, electrons cannot move into an already filled state. If i assume that somehow I fill in all the energy states in the conduction band (Population inversion :confused: )and then apply an electric field what happens?? Thanks...

A solid sphere of radius a is immersed in a vat of fluid at a temperature T_0. Heat is conducted into the sphere according to dT/dt = D(d^2T/dr^2) (d-> partial derivative btw) If the temperature at the boundary is fixed at T_0 and the initial temperature of the sphere is T_1, find the...

I'm supposed to show that the degeneracy of the energy levels of conduction electrons at fixed k_z[/tex] in zero magnetic field is given by \frac{2L_x L_y}{\pi \hbar ^2} m \mu _B B Where the energy levels of the electrons are of the form (approximation): E_{n,n_z} = E_n(k_z)=...

Hi folks, I was just looking into conduction as part of an electric shock, as in, the flow mechanism, when I ran across an article about such things, which states: "However, NO ELECTRONS FLOWED THROUGH YOUR BODY AT ALL. The electric charges in a human body are entirely composed of positive...

Sir, 1) Two spheres of different materials, one with double the radius and 1/4th wall thickness of the other are filled with ice. If the time taken for complete melting of ice in the large sphere is 25 minutes and that in smaller sphere is 16 minutes, what is the ratio of the thermal...

Hi all, If we state that low (drift) speed free electrons are responsible for the transport of power than it follows we need big forces. Regardless the explanation of what happens inside a wire i.e. classical / semi / qm etc. as far as I’m concerned this wire is a box in which I push small...

Help with Heat Conduction Question My question is: These days they reinforce concrete walls with steel bars. Would the steel bars enhance or degrade the insulating value of the concrete wall? Explain? Metal is a good conductor and concrete is a good insulator. My answer so far is that it...

Can anybody explain to me why holes are found at the top of the valence band, whereas electrons are found at the bottom of the conduction band.

A thermal window with an area of 6.00 m2 is constructed of two layers of glass, each 4.00 mm thick and separated from each other by an air space of 3.00 mm. If the inside is at 20.0°C and the outside is at -38.0°C, what is the rate of energy transfer by conduction through the window? i am...

I have been reading a number of aerodynamic texts, and it seems that everything in a fluid (gas) is transmitted by molecular collisions. Pressure is a result of molecules colliding with each other and the walls of a container Viscosity is caused by collisions between molecules in layers...

I am trying to find a way to calculate the Ec for intrinsic silicon at room temperature. I can't seem to find anything in my textbook for that. I have searched on line and the closest thing I can find is E_c = E_g + \frac {\hbar^2 k^2}{2m_e} I know what Eg = 1.12 eV for intrinsic silicon at...

I read on Wikipedia: Is myelinated interneurons redundant? If not, why? What's being done about getting this stuff into human brains? How is this myelin different? - Wah! mk.

I'm having difficulty figuring out how to work this problem: Assume a material has a given E-K diagram: E(K)conduction = Ec + E1 * sin^2 (Ka) E(K)valence = Ev - E2 * sin^2 (Ka) a=0.5nm E1 = 5eV E2 = 4eV I have to: * sketch the E-K diagram for the first brillouin zone (-pi/a < k <...

Given the 3-D rectangular solid with sides of length a, b and c in the x, y and z direction respectively. Find T(x,y,z) in the interior of the solid when laplace T = 0 Boundary condition are following conditions: 1) x=0, T=0 2) x=a, dT/dx=0 3) y=0, dT/dy=0 4) y=b, dT/dy=0 5) z=0, T=0 6)...

Anyone please explain to me what is conduction band and what are conduction band electrons? What energy do they have and how do they transfer it?

A styrofoam cooler (K = .030 W/mo C) has an average surface area of 0.465 m2 and an average thickness of 2.0 cm. About how long, in seconds will it take for 4.10 kg of ice at 0oC to melt in the cooler if the outside temperature is 28.0oC? delta Q/delta t = (k*A*deltaT)/d delta Q = 333 J/g...

hey, can anyone help me with this question? I am really having trouble with it. 1. Two metal rods, one lead the other copper, are connected in series (end-to-end). Note that each rod is 0.525m in length and has a square cross section 1.5cm on a side. The temperature at the lead end of the...

Could anyone help me solve the following problem? Calculate the ratio of the conduction current density to the displacement current density of the electric field E = E_0 \cos(\omega t) in copper, to a frequence of f = 1 kHz. (Given: \epsilon_{Cu} = \epsilon_0, \rho_{Cu} = 2 \times 10^{-8}...

Hi; Could somebody please help me with the following question: During the action potential, Na+ ions move into the cell at a rate of 3.03E-7 mol/m^2*s. How much power must be produced by the "active Na+ pumping" system to produce this flow agaisnt a +33.9 mV potential difference? Assume that...

Approximately how long should it take 8.78 kg of ice at 0oC to melt when it is placed in a carefully sealed Styrofoam icebox of dimensions 27.2 cm x 35.7 cm x 51.2 cm whose walls are 1.20 cm thick? Assume that the conductivity of Styrofoam is double that of air and that the outside temperature...

I'm doing a projekt on heat conduction i a box. The point is to simulate a house very simple. We have time varying temperature conditions on the outside, and want to model the temperature inside the box over time as outside temperature changes. The box will consist og an outer wall, insulation...

Apparently my lecturer has given me this type of quest and i really have no idea how to do this quest..anyone know the formula for conduction current..displacement current and loss tangent..please give me brief idea how to do it...what i know is that for displacement current i have to...

Hello friends I have a problem and also know its answer but I have some trouble figuring it out. Here goes Two vessels filled with different liquids are at temperatures T_{1} and T_{2} respectively. They are joined by a metal rod of length l; area of cross-section A and thermal...

Hey - do you think anyone could help explaining the process of conduction and radiation, convection currents for me? Physics exam next Monday, and I have to start studying soon! Also, what is density measured in? Kg/M^2? Thanks in advance!

Hi, these two questions have been boggling me for a week.. if anyone can I help I'd be very appreciative. The first one is.. A cylindrical rod of length 1.5 m and radius 0.02 m is insulated to prevent heat loss through its curved surface. One end is attached to a thermal reservoir at 573...

How can I calculate BTU value generated from 1 inch copper pipe with the length of 1 foot through which 176F hot water is passing?

When Maxwell showed that light was an electromagnetic wave it was necessary to identify some oscillator of atomic proportions to account for these waves. Henri Lorentz , considered that electrons which are normally held in an equilibrium position are capable of vibration when displaced under...

I thought the thing that makes a metal more conductive is the number of free electrons... How then is copper more conductive than iron when copper has only 8.47 (x10^22) free electrons per cm cubed compared to a massive 17 for iron? If someone could explain this to me my face will go like...