Vacuum Definition and 1000 Threads

I'm not exactly sure how a vacuum works. I understand that there are machines (motors?), as in a vacuum cleaner, that suck air. There are other vacuum designs though, if I am not mistaken. It is these that I am not sure about. So how do these work?

Homework Statement What is the likely main residual gas constituent of a high vacuum system (HV) (P~1x10-4 Pa) and where does it come from? Explain how the vacuum may be improved to give ultra-high vacuum (UHV) (P~1x10-8 Pa). What is the likely main residual gas constituent of ultra-high...

Hi what constitutes a vacuum? I mean it has to be made of something, since it it part of the space time continuum. In school you learn that a vacuum is empty space or area without matter, but it occurs to me that a vacuum must be made of something and there must be something there. What is it...

Assume you have a weightless constant volume container "filled with" vacuum. If you let it float in the atmosphere, how "high" would it go? I guess at some point Archimedes' principle should fail. What do you think?

I would like to try and set up a pressure control system in my lab using house vacuum and compressed air. Or otherwise using a compressed air source and vacuum pump. I want to be able to control the pressure in a reservoir (a syringe) within the range of -15 to +15psi. I was thinking...

Hi guys. I was wondering, what happens to the temperature of a object if it's put into vacuum? Say you have a box of steal (something that transfers thermal energy fast between the inside and outside). Inside the box you have a rock. The rock is held in the center of the box using...

Homework Statement I am trying to derive the line element for this geometry. But I am not sure how to show that ds can't contain any crossterms of d\theta and d\phi Homework Equations ds must be invariant under reflections \theta \rightarrow \theta'=\pi - \theta and \phi...

Homework Statement What is the de Broglie wavelength of a neutron that has fallen 0.60 in a vacuum chamber, starting from rest? Homework Equations Not entirely sure λ=h/mv The Attempt at a Solution I can't figure out what the velocity is, I think it would have to do with the change...

Homework Statement So, I was sitting in my algebra based college physics class and we were talking about buoyancy. According to Archimedes' Principal, "an object that is completely or partially submerged in a fluid experiences and upward force equal to the weight of the fluid displaced."...

hello, i have no bubbles in distillation of phenylacetone under vacuum, the heat is about 120c, and the vacuum pump produce around 20 torr. is that normal? please help me

Hi, I am using Hartle to study GR and at one point, there is a leap that I don't understand. He finds the result for the geodesic deviation equation and introduces the Riemann curvature tensor. Then, we are told that there is an object called the Ricci curvature tensor which is a...

Homework Statement An atom H has a charge +q (=proton) and -q(=electron). q = 1,6.10^-19. The electron is circeling around the proton at r distance r = 0,53.10^-10m. What is the force as a result of the electrostatic interaction between the proton and electron Homework Equations...

hi to everyone, i have the following question, see attached image. a vertical pipe containing water is exactly 28ft tall. at the top (A) the pipe is tight shut. at the bottom (B)the pipe is open and ends in a bowl of water. since no air can enter the pipe, the water remains within the pipe...

Hi We can derive equation \nabla.D=\rho_f from equation \nabla.E=\rho/\epsilon_0. But what about Ampere's law? I tried to derive \nabla\times{H}=J_f+\partial{D}/\partial{t} from \nabla\times{B}=\mu_0J+\epsilon_0\mu_0\partial{E}/\partial{t} but I could not. This is strange because I thought...

I always thought that the quantum vacuum was absolutely nothing. But I have heard that the quantum vacuum is not nothing and contains energy although it is the lowest state of energy. I am not talking about the fluctuations rather I am talking about the vacuum itself. Also do quantum...

I'm trying to build a vacuum chamber for chemistry purposes. This isn't exactly for school, but it's something I'm doing for fun and it's close enough to a school problem. Anyway, my vacuum chamber will be a prism 24" wide, 18" deep, and 18" in height. It will also have a 8"x6" Plexiglas window...

Does inverse square law apply to light in vacuum?

Sorry if I am asking a too trivial question! I am having a confusion regarding the following-The solution to Einstein equation in vacuum is given by the Schwarzschild metric. However, what does the mass represent in the metric in Schwarzschild coordinate? Whose mass is it and how does it enter...

I've been enamored with the idea of vacuum balloons for the better part of a decade. I know they're an extremely difficult engineering challenge, and may not actually be possible even with the strongest materials. I've come across a novel approach to the problem, and I'm curious what actual...

A few questions for anyone kind enough to reply and help me understanding this matter: 1. Since electromagnetic waves in vacuum have a maximum speed is this speed limited by the permittivity and permeability of the vacuum? 2. Or is it related to the density of the vacuum as it is for waves...

I got the following for the units of Vacuum permeability: H•m−1 A2•s-2•kg•m T•m•A-1 N•A−2 V•s•A-1•m-1 Wb•A-1•m-1 Does anyone see anything wrong with these units? Are the SI base units correct? A2·s4·kg−1·m−3 in SI base units Should it be (Amps)-2 power?

Homework Statement Compare the electrostatic energy of two opposite charges e and -e, a distance 7 angstroms apart in water at room temperature and that in vacuum (express the energy in terms of Bjerrum length) Homework Equations E = 1/(4(p\pi\epsilonD)*(-e^2)/r^2 ? The Attempt at a...

I was reading Mandle QFT book, and it says: "If we require the vacuum states to be invariant under Lorentz transformations and under translations, then this field must be a scalar field, $\phi(x)$, and its vacuum expectation value must be constant". Could anybody explain to me why is that?

Hello Everyone, I've been asked to work out a problem about vacuum energy <0|H|0> where H is the energy density of harmonic oscillator. When I integrate this expectation value over space of finite dimensions L, I get that the expectation value for the vacuum energy scales as L^3 . Does...

I am trying to prove a concept that was presented in my course but I am having a bit of an issue with understanding the final result. The concept was that in 3 dimension the vanishing of the Riemann tensor leaves only the trivial solution for the vacuum equations. I started by subbing Eq.(1)...

Goal --> Constant Vacuum in a Chamber Im working on a art piece that requires that I keep a constant vacuum in a chamber. I will soon have a pump and the chamber required but i was hoping someone could point me in the direction of a regulator that would hold the vacuum. The piece requires...

In my general relativity course the point was mentioned that in dimensions less than 4 the vacuum field equations cannot be constructed. I was wondering if someone knew why this is so?

What do you guys think of this new model? [4] arXiv:1209.2802 [pdf, ps, other] Expansion History with Decaying Vacuum: A Complete Cosmological ScenJ. A. S. Lima, S. Basilakos, Joan So Comments: LaTeX, 11 pages and one figure Subjects: General Relativity and Quantum Cosmology (gr-qc)...

Hi all, I am working on thermodynamics problems, and can't even seem to figure out how to start it. I came across a scenario in which an 100gallon aluminum horizontal half-filled diesel fuel tank imploded because the vent was plugged. I know the basic concept behind the happening, i.e...

hi to all, this one may sound silly but i just can't seem to understand how it will work out. this is the setup - in a vertical water column (state of vacuum) a hollow box is attached to the base. all air from the box has been sucked out and the box contains a vacuum(fig A). if the lid of...

hi to all, i have been trying to find some similar project solution on the internet but so far have found nothing, so i am posting here. here is the setup ( see attached picture) : in "fig 1" a metal chamber, perfectly sealed contains inside it a balloon filled with air (red color). the...

Just looking for a bit of advice on a problem I am currently having. I am doing some research into the condensation characteristics of steam when under vacuum. However, I am having difficulty maintaing the desired level of vacuum of around 0.06Bar in my current system. Anytime I achieve the...

Hello all I've been reading about the quantum vacuum plasma thruster. On the surface it sounds great. My question is, well, is it legitimate? I don't have the expertise to give it a yea or nea. Could someone who knows what they are talking about give me an answer. It seems like a miracle...

There is a common free fall demonstration that involves a long evacuated cylinder, a coin, and a feather. The tube is plexiglass and so the fall of the coin and feather can easily be seen as synchronized. I'd like to put one of these together, but was curious about the vacuum needed for a...

Job Description: The goal of this research is to develop a multimodal analytical platform. The postdoctoral scientist will develop microfluidic systems for cultivating and characterizing biofilms and bacteria using multiple analytical techniques. The main workload will be dedicated to the...

Hello, I am not yet well-versed in quantum theory of the vacuum, but I certainly have encountered it everywhere I have turned in my studies. Since my electron paper is unwieldy I want to run by folks my thoughts of percolations in the vacuum. So many people have spoken of "electrons and...

Hey guys, I am currently trying to figure out how to build a really small vacuum system and trying to maximize the suction force. I understand that in order to create the vacuum suction force we must have a pressure drop within the chamber so the molecules rush into the low pressure region...

Hey guys, I was looking online at sparks and how they form, and the amount of energy needed to form them when this question came up to my mind. can a spark form through vacuum? or it actually needs particles to go through them? and if it can form...what is the value of the breakthrough for...

I'm working on a home/shop use vacuum pick up system. I need to suck up some spherical objects about 3" in diameter which weigh about 2 oz. First thing I want to do is size the blower for this project. Ignoring the losses of the hose I can calculate the velocity of the air at the inlet of...

Hello, I am currently working on a pulsed laser deposition (PLD) system whose volume is approximately 115 to 120 liters. As you can assume, there are a lot of ports in the chamber but a lot of them are windows or blanks (2.75, 4.5 and 6 inch). Significant ports (possible sources of leaks...

I was wondering about the how the suction works? I got this cordless vacuum broom for free and it has terrible suction. It runs on like 7 or 8 recharge c battery's and I was wondering if i increased the amperage or voltage would the motor run faster and have more suction?

I read that some metals, if sufficiently smooth, will become become cold welded upon contact in a vacuum. What process causes this?

Homework Statement There are two particles side by side in a vacuum with electric charge q and mass m, traveling at distance d apart, with v speed(less than speed of light). What is the ratio of magnitude of magnetic to electric force the particle exert on each other? Homework Equations...

Hello all, Superconductors are great, but obviously its tricky to keep them at such a low temperature for extended periods of time. This poses a problem for engineering applications. What about the feasibility of cooling the superconductor, then placing the material in a vacuum chamber...

Hi guys, I am interested in designing a chamber that is either purged with nitrogen gas or vacuum sealed that encloses a thin film sample. The method of analysis is via ellipsometry. (My knowledge of optics is extremely limited but know that ellipsometry measures some shift in polarization...

If a cylindrical vacuum chamber's diameter is increased, then the inward force on the two ends will increase because the area is increased. However, if the length of the chamber is increased, while keeping diameter constant, will that increase the net inward force on the chamber? Or does...

I have a question I long pondered and couldn't find any explanation to exactly what I want. We all know that atmospheric pressure is due tu gravity acting upon everything on earth. this pressure act from all directions on all our body molecules. However in space there is no gravity, no...

Question: How can I estimate the amount of air that leakes into a vacuum vessel. I know the pressure outside the vessel (1020 mBar), the pressure achieved in the vessel (10 mBar), the pumping speed of the vacuum pump (400 cubic metres per hour) and the duration of the leaking (6 hours). Volume...

Preface: I understand that regardless of any further details, the correct answer is "No, it does not, because..." I'm looking for an answer because clearly I don't understand something about either thermodynamics, mirrors, or black body radiation. In my mind, the scenario I describe follows the...

The syringe' plunger is in a fully retracted position (non-vacuum state) and is then connected to the tube forming an airtight seal. Then the valve to the vacuum chamber, having 29.9 Hg of vacuum, is opened. I am fairly, certain that the plunger in the syringe will move to its forward most...