Vacuum Definition and 1000 Threads

Homework Statement A sphere is enclosed in a bell jar half filled with water. The sphere floats. Air is pumped out to create a vacuum above the water inside the bell jar. Will the sphere float in the same way, float better or will it sink? Homework Equations - The Attempt at a...

Is it possible to derive the value for vacuum permittivity(εo) without using the speed of light.?

Hello, I have read that vacuum cleaner makes 70 dBa and earplugs can easily go beyond this. The problem I have is that I can hear my neighbor's vacuum cleaner thru wall easily. But if I set my mp3 player at max (should be around 100dBa according to manufacturer) I can heard this at few...

Hello It seems we refer to the outer space as "the absolute vacuum." I read recently that the deepest vacuum man reached on the Earth is about 1000 molecules per cm3. To obtain this there was needed energy sufficient to reach a pressure of 400 billions Bars. Why space ships do not burst like...

In GR there is made a clear distinction between a vacuum region and a non-vacuum region as one is handled by the Ricci tensor and the other by the Weyl tensor. But is reality so black and white? And when do we realistically talk about dust and when about fluid? So the inside of an average...

What is the formula to calculate gas (air) density at negative pressures, as well as water content ? For instance, a vessel with air with volume of 1 m3, density 1 kg/m3, and water content 10g /m3 get vacuumed from 1BarA to 0.1BarA isothermally.

Ok guys, I need help. I work for a Contract Manufacturer that is working to solve a problem for a customer of ours. The customer has designed a snowglobe (it's actually in a jar) with a cool little Christmas tree inside it. It's a great idea, but there are a ton of nooks and crannies that...

I want to find a book that explain how the different grids affect the operating characteristic of the power pentodes. Most just give the optimal setup and states what is the output and most designer never vary away from this. I want to be able to play around with the different grid voltage to...

Think about it. If space was a vacuum how would energy from the sun (which has a mass equivalency) be radiated. Supposedly devoid of matter this is still energy which makes matter and almost every day we see the sun as something in our physical realm. Are there experiments detailing what happens...

How are internal lines with no free ends of Feynman diagrams of the perturbative expansion of QFT related to the quantum tunnelling barrier's negative kinetic energy and the HUP of QM? (if they are related at all)

Can this work?? Moving in a vacuum Okay, so i have been bugged by this idea for about a week now. And unfortunately it has been quite some time since I took any real in depth science classes. I am wondering if this idea is even plausible. In the vacuum of space, would you be able to have...

This question is really out of curiosity, and also due to my very limited knowledge of basic physics(biomed sciences tend to not teach you this). Say I wanted to create a vacuum inside a metal cubic casing with the following parameters: -The case is a cube, that measure 1x1x1m, so has a...

the pressure inside a 2 lit container has to be maintained at 0.01 bar. For this purpose, a vacuum pump will be used to pump the air outside. Also, air from atmosphere is leaking back into the container at 1 lit/min. one of the following pumps has to be selected. A. pumps out 10 lit/min...

Googled it and I was getting the vacuum pressure is 29.921 in of HG (Gage). Corresponding conversion for the other units are zero, from here http://www.engineeringtoolbox.com/vacuum-converter-d_460.html" Can anyone please tel what's the vacuum pressure in psia and psig? Any comment will be...

Everyone knows that particle-antiparticle pairs are supposed to be able to spontaneously pop into existence from "nothing", exist whilst the uncertainty principle allows it, then recombine and annihilate. Is it really spontaneous though, or has any thought been given towards whether this is...

Usually when studying thermodynamics and statistical mechanics of a macroscopic body one uses a "heat bath model" to define a temperature. In quantum mechanics one can assume that the heat bath has arbitrary low temperature. When studying quantum electrodynamics one has vacuum fluctuations...

Hello, sorry for bad english. I have probably a very stupid question :) Let's place two magnets in vacuum (empty space) How does one magnet "know" of the other one, if there is "nothing" between them? How "nothing" that exists between them can interact with magnets? I know of course...

would a baloon or a barrel 'filled' with vacuum act as a hellium balloon and float in air? of curse that would require hard shell balloon... density of air at sea level is 1.22521 kg/m3. so if we could make a vacuum chamber one m3 big that would weigh 1.22 kg it would float right...

As the usual argument goes, as I understand it, everything can be expressed in units of G, h and c. (though this argument exclude the particle masses from consideration.) The permittivity of the vacuum seems to be independent of G,h,c. Am I wrong?

I would like to know if there is a formula or a way to determine the amount of insulation a vacuum of 1 bar can produce. please note I am not talking about vacuum insulated panels.

Homework Statement Homework question for a graduate level atmospheric science course: A mercury barometer of height h has an imperfect vacuum above its mercury column so that it measures a surface pressure of 29.80 inches Hg when the true surface pressure is 29.90 inches Hg, and it...

I have a venturi tube and downstream of it, there is a small secondary opening at the end of the throat. This is where the local vacuum is created as the velocity increases and the pressure decreases. This difference between this pressure and the atmospheric pressure will induce air into the...

If an attenuated laser pulse (with expected number of photons <1) is incident on a perfectly efficient detector, and the detector does not click, does it mean we know the |n=0> state was realized, and does it imply that all subsequent detectors measuring this pulse will also not click?

According to Weinberg's logic, quantum fields are just convenient building blocks of constructing a Hamiltonian which can give a lorentz invariant S-matrix, then why must we consider vacuum filled with quantum fields and say there's no true vacuum since there's always fluctuations of quantum...

Air weighs about 800 times less than water, 1 litre of water weighs 1000 gms approx. while 1 litre of air weighs 1.25 gms approx. So theoretically it should need less energy ( in fact a lot less) to create a rough vacuum in a given volume than it would need to remove a liquid (water) from the...

If one had a high enough electric field could one pull electrons and positrons into existence out of the vacuum? The field needs to be high enough to accelerate the virtual particles away from each other strongly enough so they don't get a chance to recombine. If a particle has...

Hello all ! Help me please. I can not understand – which particles are entangled in this case http://prl.aps.org/abstract/PRL/v106/i11/e110404 Full text here http://arxiv.org/PS_cache/arxiv/pdf/1003/1003.0720v1.pdf

Hi everyobdy. First, forgive me for mistakes, since English is not my native language. I'm going to ask a kinda strange question, so let me add a short premise. I'm a first grade MD, andrology will be my area of expertise. I have to give an advice about a patient who has Peyronie' disease...

Hi, I'm building a lens and stupidly rinsed one component before putting the lens body together with epoxy glue. Now when I leave the lens in the sun the trace of water left in the vacuumed lens body turns into condensation and blurs out the vision. I've seen loads of forums suggesting using...

I have a product that we perform submersion testing on to determine susceptibility to water intrusion. The product is heated to 120C and then placed in an ice bath. I have measured the pressure / vacuum during testing and have determined that the pressure can rise to 5 psi while heating and...

This is something that has popped into my head recently. afaik, vacuum tubes were once the most common device used for switching, and amplifying. Then transistors and other semiconductor devices come along and almost wiped out vacuum tubes (not totally i think) what I want to ask is...

http://www.physorg.com/news/2011-08-dark-illusion-quantum-vacuum.html "His ideas (like those in the previous paper) rest on the key hypothesis that matter and antimatter are gravitationally repulsive, which is due to the fact that particles and antiparticles have gravitational charge of...

Hi: I’ve been trying to figure out how does the spinning action of the turbine blades in the video produce a vacuum so as to draw air down the shaft? I don’t see any venturi effect taking place. A bit puzzling on how this gadget works?:confused...

hello I have to deal with a vacuum pump in my graduation project & i don't how ?? shall one help me with all my respect & greetings , i want to know the inlet , the outlet & the electrical connection of this vacuum pump the rest of the pic in is the next reply

This conundrum will sound hypothetical, but it represents a real-world problem: You have a pump sucking water through the same diameter line from the same level in 2 different places in a pool. FWIW, the pump is a Hayward Super Pump Series Model SP2607X102S...

Homework Statement Electric and magnetic fields in many materials can be analyzed using the same relationships as for fields in vacuum, only substituting relative values of the permittivity and the permeability, ε = κε0 and μ = κmμ0, for their vacuum values, where κ is the dielectric...

Say there was a theoretical soda can made of a super strong material that could hold up to the pressure of the atmosphere while weighing the same as a regular soda can. If everything was sucked out of the can, would it float in Earth's atmosphere? I think physics says it would float, but tell...

Do magnets have a longer reach of attraction in a vacuum chamber?

Wikipedia says: second paragraph here: http://en.wikipedia.org/wiki/Dark_energy Vaccum energy (density) can vary over time and space? Is that accurate? I've read the cosmological constant can vary, but not vacuum energy.

So apparently vacuum energy is created and destroyed within Planck time by matter, antimatter annihilation. If someone could theoretically stop or slow down time, would it be possible to tap into vacuum energy? Since annihilation creates gamma rays, I suppose vacuum energy would face the same...

Hi I am new, I've read the FAQ's and none of them seem to help. Its a classic question I know but I can't seem to find a full answer. I understand that light is part of the electromagnetic spectrum I also understand that light acts as both a particle and a wave. I think I understand the...

Hi, Someone told me that a potential of 10^6 volts is not stable because it would cause spontaneous electron-positron creation from the vacuum. Is this true? I thought one could reach higher potentials than 1000000 volts.

Is it possible that even in a vacuum that the void space in the vacuum could consist of some other material? What is the median on which gases move, what is the nothingness in between atoms?

Any object rotating on the axis does stop because of some kind of friction force. What happens if the same object rotates in the vacuum ? does the friction force applies to it ? or does it stop at any point in time ? or does it continue to rotate forever ? Thanks & Regards, Niral Soni

So I'm degasing a solution in a glovebox. The way we did it is get a rubber septum that can cover the bottle opening. We stuck a needle through the top of it, as well as a glass tube with a porous end. We used the needle to create a vacuum in the bottle by hooking up it up to a pump. The glass...

hi, I have learned that temperature defined by man is a measurement of average kinetic energy of particles, how about that in a space that is no particles at all or just a very few number of them? What readings will we get if we put a temperature-measuring device in a highly vacuumized...

Hello! I was thinking about what would happen if an atomic gas was allowed to expand in vacuum and concluded I don't have much of a handle on the subject, so if anyone would help me out - I'd really appreciate it. So, let's say we have an ideal gas in a container located in vacuum...

Stuff like osciolloscopes, vacuum pumps, plumbing/tubes/joints, soldering guns, etc. that it would be nice, cause it takes some time to find all these manuals, and filter the information... *instruction manuals (in title)

Hi, I would just like to know how did Geiger and Marden create a vacuum for alpha particles during the Rutherford scattering experiment? Also, when Rutherford discovered the alpha particle did he know it had +2e charge? Any help would be appreciated. I've looked everywhere for the answers but...

Do fields have quantum fluctuations and are non-zero in the vacuum? Non-zero in the same way that for a harmonic oscillator the wave function is non-zero for values of the position of the harmonic oscillator? Or are they considered as 'mathematical fiction' just as 'virtual' particles? thanks