Measuring Definition and 1000 Threads

If I'm correct, a series of with respect to some property entangled particles exhibits a correlation between several measurements of that property by means of two measuring devices. My question is: is it possible that between measurements the physical constitutions of the measuring devices...

Let's say I have a simple small DC motor. If I measure the current by putting two multimeter leads on the positive will it be a different value then if I were to measure it on the negative? My guess is that the current measured on the negative lead will be lower because the energy used in...

Hello, I am currently working with magnetic nanoparticles that aggregate and can be measured on the micro scale. Part of the project involves measuring their velocity as it move through vrious liquids. My current set up is simply timing their distance traveled. Does anyone know of a more precise...

Is it possible to build an apparatus that could do the following (at least ideally in principle)? If so, what would it be like? A fairly localized light wave packet (with a corresponding spread in momentum) reaches the origin of our coordinate system from any direction in the XY plane (taking 2...

I have a word problem to solve and am thoroughly confused. any input would be great... My younger brother had a run in earlier with Médecins Sans Frontières. He narrowly escaped from an adverse verdict by the court... What he wants is that he be left alone to run his small café... He asked...

Hi, if I have a block of metal with a quarter circle curve cut out of it, and a metal roller of matching radius that contacts this curved piece, what are some ways I could go about measuring the friction between these two surfaces? The roller is fixed and the block is pushed into it with a...

What is pain threshold? Can pain be measured? If so, how? What are the units? Thx :-p

I'm looking to measure the weight of an tennis racket at different lengths. Obviously If I stick it on the scale it will give roughly the sam,e weight no matter if I put the whole racket on, or a third of the racket. Would there be a way I could measure the weight, of say the first third of an...

Let's suppose that we have an entangled state of two systems ##A## and ##B##: $$ \frac{1}{2}\left(|\psi_1 \phi_1\rangle+|\psi_2 \phi_2\rangle \right) $$ where ##|\psi \rangle## and ##|\phi \rangle## are energy eigenstates of ##A## and ##B## respectively. However the eigenstates##|\phi_1\rangle##...

Guys, is it accurate to measure the battery's emf by putting voltmeter across the battery( it is not connected in circuit). I think this is accurate because there is no current flowing, this means that there is no voltage across the internal resistance.

Hello, I am new in this field, so maybe my questions will be stupid :) sorry for that :) In the company where I work, they measure flow rates of wastewater using Flow meter (Doppler device). The problem is, that the flow rate is very low, so this device is not submerged completely in the...

Homework Statement Measure the density if air at normal atmospheric pressure. You can use the following equipment: One scale with an accuracy of 0.01g Two empty glas bottles (≈0,33 liter each) One big bowl with water One cork with a valve and a vacuumpump Homework Equations Not knowing how...

Homework Statement Hi all, I'm currently working on a Hall effect lab in which I analyze a p-type sample of germanium (I know it's p-type because I observe a hall voltage inversion point around 350 K which can only happen for a p-type sample). From the Hall and resistivity data I can obtain...

I was experimenting with resonant frequency of a series RLC circuit: 5V AC source 10 ohms resistor 100microF capacitor 46mH inductor Resonant frequency is calculated to be around 74.2Hz. So I set the AC source to resonant frequency 74.2Hz and measured the voltage across the 10 ohms resistor...

Greetings everyone. I'm working on a project that requires the very accurate measurement of distance varying between 0.500'' and 0.050''. I need to measure the distance within at most 0.010'' tolerance and give the value digitally. The read-rate is once every second. I'm on a very tight budget...

When we take pressure readings by pressure gauge (Bourbon pressure gauge or pressure transducer) in the laboratory for any fluid system ,in this case, is the atmospheric pressure value (1 bar) must be added to this readings when we use them in any calculations later or them must be used...

Homework Statement Homework EquationsThe Attempt at a Solution I'm fine with parts a) and b) However I don't understand what part c) is asking me to do. How do I 'measure' an operator? There are only two things I can think to do: 1. Find the expectation values of A for <Φ1|A|Φ1> and...

Hi, Does anyone have any suggestions on how I could measure where the boundary layer transition is over an aerofoil. Preferably by flow visualization techniques. The flow will take place in a low speed wind tunnel. thanks

I bought a PH meter with glass electrode. I calibrated it using a buffer solution following the instructions. When I measure the PH of tap water, vinegar, or other simple liquids it initially keeps changing but eventually it stabilizes at the correct value. But I tried to measure gastric juice...

Homework Statement The diameter of our disk-shaped galaxy, the Milky Way, is about 1.8E+5 light-years (ly). The distance to the Andromeda galaxy, which is the spiral galaxy nearest to the Milky Way, is about 1.8E+6 ly. If a scale model represents the Milky Way and Andromeda galaxies as dinner...

Homework Statement We are supposed to figure out the voltages over every resistance when measuring with a voltmeter Homework Equations R1=R2=10k ohm R3=R4=100k ohm R5=R6=1M ohm R7=R8=4.7M ohm U=10V The Attempt at a Solution The thing I'm not quite...

Hi, I am working on a project where I've to make an electromagnet and very very low amount of current (micro amp to nano amp) will be supplied to the electromagnet. And finally have to measure the magnetic filed with a sensor. My question, is it feasible to generate measurable magnetic field...

I am having a question concerning multiple measurements of the period of a pendulum, for let's say the determination of g. Let's say I am using a stopwatch with an uncertainty in time \delta t and I measure 10 times the period of the pendulum: T_1, T_2,...,T_{10}. Are the two following...

Without getting too deep into the physics or philosophy of quantum mechanics, and I'm NOT talking about theory (no 'what the equations say') but if I'm not looking at my couch does that it mean at the moment it doesn't exist? Or if I'm not looking at my dad he isn't there but in the form of a wave?

Hi, Apart from the redshift of electromagnetic waves (which we do observe), is there any other evidence of space expansion that is not based on redshift? If not, is there a theoretical experiment that could let us observe and measure space expansion? Here I am assuming that space is not just...

We are currently trying to measure pH levels on the (wet) surface of metals as part of a study about corrosion. The surface may have a non-conductive protective layer. - is it feasible to measure pH on a planar surface (dry or wet)? Which kind of sensor probe can be used for this task? -...

Hi! I found a nice thing via google for a measuring forces by using a light pipe. The light gets coupled into a light pipe and the amount of light is measured by a diode (http://www.dr-iguana.com/prj_LightPipe/). I think you can also use such a device for measuring the deflection of a membrane...

Good morning, I have an iron bar (35 cm long) hinged on an axis. The path of this bar is limited to 45 degrees. I have to measure the angular velocity of the bar when it rotates 45 degrees. I need to get a graph of variation of the angular velocity along the 45 degree paths. The time taken to...

Homework Statement My (practise) coursework is to test the equation 'V = Vo e-t/RC' and choose values of R and C so that the voltage across the capacitor falls to half in 15 seconds. I decided it would be too difficult and inaccurate to record the voltage across the capacitor every 5 seconds...

I have an electric motor that I am using to turn an auger to dispense pet food. I want to measure the average torque required to turn this auger at a given rpm. I know Powerin = Voltage into motor * Current into motor and Powerout = Torque exerted by shaft * RPM of auger and Powerout...

The meters used in measurement have some level of accuracy. There is a probability distribution of measuring the true value, and that distribution curve for the accuracy of the meter has some standard deviation. And the component being measured also has it's own manufacturing distribution that...

Hi, PF! I recently solved a problem from BSL which asked to analyze the following system used for determining the diffusivity of a binary mixture of gases. The left portion of the system, from the left bulb up to the stopcock at the middle of the tube, is filled with gas A. The right portion...

Not sure if this is an engineering or physics question, but here it goes: I'm trying to wrap my head around the pressure field caused by waves. I'll recap to so anyone can check if I have made any incorrect assumptions: If we ignore atmospheric pressure, the pressure in the water has a...

I am having trouble understanding how a gravity wave detector can be de-coupled from the wave it is intended to measure. For the sake of conceptual discussion, if I am eyeballing a ticking clock some distance away and a wavefront hits the clock and say 10 or so waves pass through the clock...

Hello PF. Prior to the train/embankment thought experiment, Einstein argues that in order to determine if events are simultaneous, an equidistant observer is required. The embankment observer is equidistant, and when the light from the two flashes reaches him he sees them as simultaneous. The...

Homework Statement You are asked to find the weight of a paper clip as accurately as possible and given ten paper clips and a scale that has a precision of 0.1 g. (A paper clip weighs about 1 g.) Which of the following proceedures would give you the most precise measurement the weight of a...

Hi everybody. I have been reading about the Stern Gerlach experiment lately and a doubt has came to my mind. Is there any way to know the spin of an electron without forcing it to interact with a magnetic field? Thanks for reading.

Hello I would like to measure a LVDS signal, on the board that is sending this signal. There are two signal pins on this board for this signal, signal-p and signal-n. How can I measure this signal? Can I use single ended probes and an oscilliscope? I tried to do that but I can't find a signal...

Hello all, I am interested in measuring the photoresponse of a transistor with a fixed source-drain bias. I would like to feed the drain current into a current preamplifier and output the preamplifier signal to another location. The preamplifier has a very low current maximum, so I will use a...

Dear PF Forum, I'm sorry if I ask the basic question here again. Just need confirmation. V = 0.6; Gamma = 1.25 TRAVEL travels at 0.6c. STAY stays. Pic 02 is Pic 01 boosted -V. 1. All STAY knows about TRAVEL is: Proper Time Speed Is this true? And mutually for TRAVEL 2. At B (and C)...

I set up a zinc-copper elctrochemical cell by placing both electrodes in lemon juice to test the ability of lemon juice to conduct a current. I used a voltmeter and attached each lead to one of the metal electrodes. What I observed was that the voltage over time given on the voltmeter began to...

Dear PF Forum, I'd like to know how to measure speed only by doppler effect. What if we don't know the frequency? What if we don't know the distance? If we look this diagram on our computer screen, we'll know everything. Distance, speed, time dilation event relative simultaneity of event. But...

Hi all, I was recently watching one of Susskind's 'Theoretical Minimum' lectures in which he says that the entropy of the universe may be measured via the number of observable photons, and that somehow these quantities (photon number and total entropy) are somehow linked. Could anybody with...

jfizzix submitted a new PF Insights post Measuring Quantum Entanglement? Continue reading the Original PF Insights Post.

Dear PF Forum, I'd like to know how we measure speed, distance clock in space? ##v = 0.6c \gamma = 1.25## Supposed the distance between A and B is 900 ls. And supposed A and B keeps exchanging signal for 6 seconds interval. Because the distance between A and B is 900 ls, there are 150 signals...

Of course our gravitational relationship with the Sun and our own Moon are understood, but to what extent can we measure even the faintest attraction with other bodies in the Solar System. How do Mars, Venus and Jupiter effect Earth? Do we have Barycenters with these bodies and others more remote?

Can someone give me a simple explanation of how to measure the Rabi probability oscillations in a two state atom?

Has electron recoil due to photon emission ever been confirmed by experiment? cause I can't find any reference to electron recoil being measured anywhere I look. If it has been measured, what methods do they use?

Is solar uv completely blocked from reaching Earth or do we just need more sensitive uv detectors to make ground-based observations? In particular of the uv wavelengths corresponding to hydrogen Lyman series lines.

Hi all, Say two events happen in the same place according to one observer (1). They are separated in time by 3 years. According to another observer (2) that is moving relative to the first, the events are separated by 5 years. We can calculate, using the invariance of the spacetime interval...