Thickness Definition and 349 Threads

Homework Statement How thick a concrete wall would be needed to give the same insulating value as 3.5 inches of fiberglass? Homework Equations Q = -A·k·ΔT/Δx k = -Q·Δx/A·ΔT The Attempt at a Solution So here, k is equal to the insulating value, and since I want the insulating value...

Hi, has anyone had any experience with visibility of single-layer flakes of graphene on substrates with non-optimum thickness of SiO2? We've been shopping for some Silicon wafers with 300 nm of SiO2, but our supplier can only ensure the oxide thickness within 10% of the specified value. I...

I'm here because I'm debating the purchase of a 1/4" thick 6061-t6 aluminum chassis reinforcement plate for a 3000# track car, versus one that is 3/8" thick. This is a chassis plate that runs below the length of the driveshaft and helps tie the left/right sides of the car together. Let's say...

Homework Statement [PLAIN]http://img714.imageshack.us/img714/7747/43416215.jpg The attempt at a solution I have already solved parts (a) and (b). It's part (c) that I can't get. To get a minimum thickness at 50 MPa, I thought that the hoop stress equation would govern. Here is my...

Hello there, I'm an undergrad in my 3rd year and I'm doing an investigation into the 'Preparation of Thin Films and their use in Hall Effect measurements.' We are making thin films of bismuth on glass (with pre drilled terminals) in a vacuum system. The way they suggest measuring the...

Hello all, I am somewhat confused in understanding the depletion region of a p-n junction diode.Everywhere a depletion region is defined as a region near the p-n junction which is devoid of charge carriers.And the formation of this region is said is explain that it is due to the diffusion of...

I'm having trouble with understanding how to calculate a wall thickness change in a hollow cylinder unde axial loading. The length, outside diameter and initial wall thickness are given as well as the size of the load, Young's modulus and Poisson's ratio. I guess this isn't really a hard...

Homework Statement An infinite slab of charge with thickness d (from x=0 to x=d) in the x direction has a charge density corrosponding to rho (x) = Ax+B where A and B are positive consants. Find the electric field at point x1<d Homework Equations I know i have to find some guassian...

Yes, first to say that this's really a basic matter but I've found all around a week & still facing difficulty, hope someone has patient to help me an answer then i can go further myself :wink: As in the attached picture, a few ones have done their calculations & showed the different wall...

How would the whiteness of snow appear if Earth's atmosphere were several times thicker? I think it would appear red as most of the blue frequency light would be scattered before reaching the Earth and the majority of light being reflected of the snow would be red. Am i right?

I'm working on some stress analysis for work. I'm analyzing the design of a plate, part of which is meant to deflect under a load. Due to this sheet metal plate being somewhat non-straight forward geometry, calculating correctly is a bit tricky. I'm putting an undercut into the plate to allow...

Hello I have done some lab work where I have coated a wire with an organic layer. The density of the organic layer is 800kg/m^3 and the density of the wire is 2620kg/m^3. I assume 1wt% of the wire is the organic layer the rest is the wire. The mass of the wire with organic layer is...

Currently in our lab we have a WEDGE shaped sample that we would like to be able to know the thickness at various points along it. Our sample is about 5mm x 5mm. The wedge SHOULD extend from one side to the other. At the highest point, the wedge is 50nm, and then drops down, hopefully at a...

ok guys, suppose i wanted to build a round 8m diameter 1m high pool out of galvanized steel sheet. I will be filling it 0.7m with water. I am aiming to reduce its cost so I am calculating the thinnest sheet i am allowed to use without it failing. I will be using 7 sheets bolted together(each...

I´m trying to find approx. numbers or formulas for a submarine like structure to mantain a constant volume. For a given volume, which materials and to what thickness should the container be?

Homework Statement To reduce reflections from glass lenses (n ≈ 1.5), the glass surfaces are coated with a thin layer of magnesium fluoride (n ≈ 1.39). What is the correct thickness of the coating for green light (510 nm vacuum wavelength)? Homework Equations \lambda = 2nd/(m+1/2)...

Homework Statement Stealth aircraft are designed to not reflect radar, whose wavelength is typically around 3.0 cm, by using an antireflecting coating. Ignoring any change in wavelength in the coating, estimate its thickness. ____cm Homework Equations Well, that's just the issue. I...

I'd like to ask does thinner convex lens give a shorter focal length? If so, why is it? thanks very much~~

Hello all, I am looking for a reference (text or peer-reviewed journal article) for the derivation of the boundary layer thickness over a short square cylinder as a function of distance from the leading edge for the simplest case of steady, uniform and laminar axial flow of an inviscid...

I was wondering if anyone could help me with the following question, please: A thin walled pressure vessel is to be used as a pressure accumulator in a number of situations all involving a number of different operation conditions some of which create cyclic stresses. The dimentions of the...

Hi, I'm constructing a waste water tank of 304 stainless steel plate and I'm not sure what thickness the material should be, the tank is approximately 2750mm x 1500mm x 1750mm What would the ideal thickness be for the 304 stainless plate and would there be any specific areas I should focus...

Homework Statement i am trying to work out the required material thickness for a given box. the material i am using is aluminium. i only require the formula - can't find a suitable one on web Homework Equations The Attempt at a Solution M = I σ y M = bd M...

1. A capacitor is formed by 2 parallel plates separated by a dielectric of relative permattivity er = 12, the capacitor plates are 5mm x 10mm. Calculate the thickness of the dielectric required to create a capacitor of 100pF 2. C = eA / d therefore d=eA/C, we have C 100 x 10-9, area of...

1. A conductive sheet of material has a CSA of 10mm x 20mm. Reisistivity of 103 (10 to the 3, 10,000) ohms M. Calculate thickness of the material required to give resistance of 5k ohms 2. Ro = RA/l , where l would be thickness, l = RA/Ro 3. Thickness = 5,000 x 0.2 / 10,000 = o.1m...

Homework Statement A thin layer of a transparent material with an index of refraction of 1.27 is used a nonreflective coating on the surface of glass with index of refraction of 1.51. What should the thickness of the material be for it to be nonreflecting for light of wavelength 510nm...

How do you calculate the thickness or gauge of a given metal (304 Stainless Steel for example) for a 36" dia. round, vertical cylinder water holding tank? If filled say the tank would be 25-30 feet tall. No physical pressure (pumps or vacuum) on this vessel (vented to atmosphere). Flat...

Homework Statement Given the density of the mantle to be 4700 kg/m^3, the density of the core to be 9700 kg/m^3, the radius of the planet to be 6050 km and the mean density to be 5240 kg/m^3, find the thickness of the mantle. Homework Equations I tried using the formula M = D * V and V...

vacuum vessel / distiller correct wall thickness?? Hello! I have a vacuum vessel / distiller type of vessel with following:- Temperature inside the vessel max. 200°C [Celcius] and a Vacuum at max. -80kPa = -0.8bar Material: SS-304 = Stainless Steel Volume = 0.654m³ My main question...

1) In a double-slit experiment, two parallel slits are illuminated first by light of wavelength 460nm, and then by light of unknown wavelength. The third-order (m = 3) dark fringe resulting from the known wavelength of light falls in the same place on the screen as the second-order (m = 2)...

In XRD, to examine the diffraction pattern and the determine the elemental structure, a thin layer of sample is deposit on a substrate. since x ray penetrate deeper than electron, how the thickness of the sample will affect the XRD result? how do know what is the appropriate thickness to...

Hello all, i need one suggestion for shielding of a gamma source. I have a gamma source with initial activity of 50 mCi=1.85X10^9Bq. What thickness of lead needed to protect myself! I used the formula I(x)=I exp(-kx). I=50mCi; k=37.6 cm^2/g (linear attenuation for 122 keV) and x the thickness...

will thickness of a thin film affect the result of xrd? if too thin, will not get the best result?

Homework Statement A beam of light is split into two coherent beams of intensity I which are in phase. The two beams are sent through different paths and superimposed at the same spot on a screen. A path difference is to be achieved by inserting a glass window of refractive index of 1.7 in the...

Hi I needed to design for a steel plate of S275 steel (275 N/mm2) that will resist a tensile force = 2 x 65 kN = 130 kN. The steel plate must not bend due to this tensile force = 130 kN. And I need to determine the minimum steel plate thickness that will resist the bending (due to the...

In deposition of thin film on a p-type silicon, how to make sure the thickness of the thin film will not affect or affect the least the electrical(Hall Effect) and structural properties? how to know how thick is the thin film that most suitable? can it be calculated? by the way, the thin film...

Homework Statement A hollow spherical shell carries charge density \rho = \frac{k}{r^{2}} in the region a \leq r \leq b. Find the electric field in the three regions: i. r < a ii. a < r < b iii. r > b Homework Equations Surface Area of a sphere Coulombs Law Gauss's Law The...

I am trying to calculate the thickness of the boundary layer for a NACA 2412 airfoil. I am working on constructing some wind tunnel tests that simulate a Cessna 172 (NACA 2412 airfoil). I am trying to determine the thickness of the boundary layer (distance from surface to 99% of free-stream...

Thickness of Quantum Well ?? As I know there are two quantum wells exist. 1. Single Quantum Well 2. Multiple Quantum Well My ques is that : How to find the thickness of a quantum well ? is there any equation to find quantum well thickness ? for single or multiple ? Usually I have look...

Homework Statement What is the thinnest film of MgF2 (n=1.21) on glass that produces a strong reflection for the light with a wavelength of 531 nm? Homework Equations Open-Closed Standing wave Fn= (nv/4L) v = Wave Length * F The Attempt at a Solution Basically, I tried to...

I understand the distinctions of the different types of material strengths, but I get stumped when asked about how they apply when the material discussed is thicker or thinner. Any help?

Hello, You've all probably seen the classic Blasius solution concerning the thickness of a boundary over a flat plate. This problem though assumes that the free stream velocity is constant. http://www.see.ed.ac.uk/~johnc/teaching/fluidmechanics4/2003-04/fluids9/2-dboundary.html I am...

Homework Statement Light of wavelength 547nm is incident perpendicularly on a soap film (n=1.31) suspended in air. What is the smallest nonzero film thickness for which reflected light undergoes constructive interference?Homework Equations 2t = (m + 1/2)(wavelength/nfilm)The Attempt at a...

Hi all, I am doing a paper on the space elevator. On the wikipedia site it states that a climber would be far better off on a stationary cable rather than having a cable pulling the climber since "the cable to be significantly wider at the center than the tips". Why does the center have to be...

1. What do we mean by the carrier number at transparency. I mean, what is carrier transparency of a laser? 2. in an IEEE paper ("Circuit Modeling of Quantum-Well Lasers for Optoelectronic Integrated Circuits (ICs) Including Physical Effect of Deep-Level Traps" IEEE J. Quantum electronics...

Homework Statement A thin film of oil (n = 1.50) floats on water (n = 1.33). If the film appears yellow-green (\lambda = 550 nm) when viewed at normal incidence, how thick is it? Given: n_{f} = 1.50 n_{water} = 1.33 \lambda_{0} = 550 nm \theta_{i} = 0 Required: Thickness (d)...

Homework Statement For a science experiment you need to electroplate a 130 nm thick zinc coating onto both sides of a very thin, 3.0 cm*3.0 cm copper sheet. You know that the charge carriers in the ionic solution are divalent (charge 2e) zinc ions. The density of zinc is 7140 kg/m^3 If the...

Hi All! Im a bit confused regarding the relationship between focal length and the thickness of a lense. In the lab that we performed, my data seems to be skewed and I am unable to decipher the trend. Can someone explainwhat happens to the focal length as the thickness of the lenses...

Homework Statement A transparent film (n = 1.5) is deposited on a glass lens (n = 1.65) to form a nonreflective coating. What is the minimum thickness that would minimize reflection of light with wavelength 500 nm in air? Homework Equations 2nt = mλ n = refractive index of film t =...

Homework Statement What are some different ways to find the thickness of aluminum foil? Homework Equations I have already calculated it by using the method that requires us to find the volume, given the density, and dividing it by area. So i need new ways to do this same problem...

Hello all, Maybe this is a simple question. I've done some calculations like this, but for heating in buildings. Now it's different. I have some crystals I must keep cold, at -25ºC. So I will surround them with an insulation material wall. Outside we have atmosphere temperature I want...