Measurement Definition and 1000 Threads

I am trying to measure the linewidth of a diode laser using the self-heterodyne technique. The laser specs says that the linewidth is ~100kHz at 1us. I guess I am confused by the "at 1us" and how exactly that translates to measuring the linewidth myself by looking at the beat note on a spectrum...

Homework Statement The uncertainty in the position of an electron along an x axis is given as 38 pm. What is the least uncertainty in any simultaneous measurement of the momentum component px of this electron? Homework Equations Position uncertainty = h/ delta p (delta p is the uncertainty in...

Is it possible to measure the vacuum energy locally? I wonder if it might change with gravity? I'm told that we can measure the vacuum energy globally by measuring the acceleration of the universe's expansion. But can we measure it locally? Or are all local measurements independent of the vacuum...

Hi, Id like to measure inrush current for various salvaged transformers (unknown windings, but probably 120/24) to the nearest 10 mA. I only have a simple DMM and soundcard scope. It seems that a clamp meter has this capability; if a clamp meter is the best approach, can I construct my own...

Has this been accurately measured yet? Google searches yield results for H 1s-2s and H 1s-3s transitions but not 1s-4s.

I know there are three definitions of humidity. Absolute , relative and specific. Can you tell me if on a typical commercial device (such as the one i have in a clock i have) that measures humidity as percentage is it the relative humidity that it measures? Can the percentage become greater...

I have a family member in a private grade school and I am organizing a teaching plan for those grades. I was struck by how measurements are integral to the learning and understanding of so many facets of physical science and math. I got good feedback from an initial try by teaching distance...

Measuring the total radiant flux with an optometer of SFH 4550 LED from osram I'm getting ~70mW, If I place 5mm long rubber hose around the led (top 2,5mm of the led is free), the power is reduced to 50-40mW. This does not make sens to me, the led has a half angle of ±3° and emits nothing to...

Hi All, First, the context for this question can be found in Wilde's Quantum Shannon Theory text on the arXiv, specifically the section starting at the bottom of page 98, entitled "Entanglement in the CHSH Game". My particular question relates to Exercise 3.5.11 on page 100 of the same...

Hi all, We are measuring our custom-made Half-Wave-Plates (HWPs) for controlling retardation error as part of incoming QC. We don't have a device for measuring retardation nor do we have access to X-ray analyzer. We have experimental result with no model supporting it; the actual question is...

As far as I understand, the Hilbert space formalism can be derived using functional analysis and representation theory (not familiar with those) from the requirement that observables (their mathematical models) form a C*-algebra and the possible states of a system map the members of the algebra...

Hi, I am new here. I would like to know if anyone can explain to me the meaning of +0.02 to +0.05 in a fabrication drawing.Does this part needs to be fabricated in this range of tolerence or,i should follow the maximum value. Appreciate your replies. Thanks.

The electron paths in the path integral formulation of qm are in ordinary space-time. The end-points of the paths in the steady states must be in ordinary space-time as well. The electron's potential is exact or nearly exact either by measurement or by calculation. The electron's locations...

Hello! If we consider a single-particle system, I understand that the measurement of an observable on this system will collapse the wave function of the system onto an eigenstate of the (observable) operator. Therefore, we know the state of the system immediately after the measurement. But as...

As I undersand it, if you make a measurement on particle and get some observable property like spin, you can quickly make a second measurement and get the same outcome. How long do you have to make that second measurement before it starts evolving according to Schrodinger's equation and you...

I'm aware there have been plenty of discussions about Copenhagen interpretation vs ensemble interpretations (myself I have always been more fond of the latter) but I intend to explore new perspectives and stick as much as possible to what QM practitioners do in practice as opposed to obscure...

I'm interested in determining the density of a dough. I want to be able to continuously measure the density of the dough as it rises. My thought was to use an ultrasonic wave and measure the time it takes to reflect through the dough I would assume that as the dough ferments and the amount of...

Firstly, I'd be happy to be corrected if I'm not using the right wording or just plain incorrect with my approach. Is it practical to suggest that units of one measurement system could possibly represent the measurement of things not only at the macro level, but represent particles with and...

Homework Statement https://dl.dropboxusercontent.com/u/62834965/neutron_interferometer.png Consider a neutron interferometer (NI), such as the Mach-Zehnder interferometer in the figure. We send in a beam of neutrons. We assume that the flux of neutrons is so low (neutrons can be very slow)...

Does anyone know of a good website or book that provides every measurement system that is still being used to this day? For example, I want to know the "how and what" when it comes to measuring cells, atoms, subatomic particles, etc,. And another question, does anyone know if there is only one...

Hello guys , have a question and I can not find the answer. In what units is measured elastic limit ? Thanks A lot !

Is there any law that prevents us from accurately measuring the momentum of a particle , just like the energy time uncertainty principle makes us observe the system for an infinite amount of time before we can be certain about its energy? I got this doubt because if we can do it, we will...

Homework Statement I am trying to find the possible measurement results if a measurement of a given observable ##Q=I-\left|u\right\rangle\left\langle u\right|## is made on a system described by the density operator ##\rho={1 \over 4}\left|u\right\rangle\left\langle u\right|+{3 \over...

Hi everyone! I am trying to find the parameters of a surface mounted PM synchronous motor using the application note AN4680 (PMSM Electrical Parameters Measurement) and had some queries regarding it. The Ld process is mentioned as follows 1. Align the rotor to phase A. Phase A is connected to...

Thank you all for any help or advice you can give. 1. Homework Statement What is the fabrication Wavefront error (WFE) of a mirror with a PV surface error of 1 um? Express your answer in terms of RMS waves at lambda = 0.633 um Homework Equations WFE=2*SFE The Attempt at a Solution I know...

I've understood that the main evidence for a non-zero ##\Omega_\Lambda## comes from supernova 1a measurements where one measures the redshifts along with the luminosity distances (equivalently magnitude) of the supernovae and, plots them against each other, then compares the result with...

Hello, Could you help me with the homework, please...For the conventional resistance measurement used four electrodes: two current (A, B) into the country "deserts" and the current I between two measuring (M, N) is then measured voltage AU, resistivity, which is the goal of our measurement is...

I am not a classroom student but study what I feel like knowing. As such I don't have access to professional teachers to ask questions like this one. The reason I ask is that my daughter has epilepsy and pulsing lights cause seizures. It is my understanding that florescent lights actually...

Suppose one scientist performs a series of experiments, and another scientist does the same thing. But unbeknown to either of them, a highly evolved alien measures all of the particles the first scientist is going to test, just before he does his measurements. Question: Would the two...

Suppose there are two scientists in a laboratory containing measuring apparatus, and there is a particle whose momentum is unknown to those scientists. (1) Does the particle have momentum before it is measured? Suppose one scientist measures the momentum of the particle, and subsequently the...

As I understand it, the Hamiltonian is the kinetic plus the potential energy of the wave function. When a measurement is done what happens to the kinetic and potential energy? Does it dissipate? Is it conserved in the measured state? Does it decrease? Does the Hamilton or kinetic+Potential...

I love measuring and quantifying the world. I'm curious if I'm missing any good, essential tools. I'm also curious of some good, affordable fill-ins for some measurement capabilities that I may be missing. I currently have: Laser Distance Measure Radar gun Scales IR Temp Sensor pH Meter...

Hi, My question is the following: As well known, the interference pattern disappears when one determines which slit the photon has gone through. This also holds for atoms and molecules. Now I understand how the actual experiment works for eg. an atom: They send excited atoms that can decay in...

What is ''faithful measurement'' in Quantum Mechanics exactly. I have seen this expression in Kochen-Specker Theorem.

Hi! Is it possible to measure phase angle in Multisim? I want to measure phase angle of current through capacitor C1: I got by hand ic1(t)=0.117*sqrt(2)*sin(2*pi*50*t-178.040deg) Thanks in advance.

It is clear from some more advanced variations on the double slit experiment (quantum erasure, etc) that retaining or destroying "information" on one half of an entangled pair affects the result of the other. The results tend to either be wave or particle type behavior on a detection device. I...

Homework Statement The Magnus formula is used for calculating the saturated water-vapour pressure Ew at temperature t. The average of the 10 repeated measurements of air temperature is 22.27 ˚C with experimental standard deviation s(t)=0.09 ˚C. The permissible error of the thermometer is ±0.3...

Hello, I am trying to understand the concepts of photometric and radiometric measurements in an electronic sensor. Various photo sensors based on CCD (Charged Coupled Devices) or CMOS photo diode array technology are available in the market for measurements in Visible Spectrum. Now I want to...

As a writer, light is as crucial as it is to physicists. But I'm struggling with some conceptual understanding surrounding light. If you could supply any answers to this science layman I would be very grateful. 1) Without light there is no way of observing and measuring. So light is both itself...

Hello! I have a question about measurement of spectrum analyzer. I made some inductor by lithography, evaporator, and lift-off process, and tried to measure using spectrum analyzer. (The probing was GSG type) I swept the frequency from 100MHz to 5Ghz, and output power was monitored by...

by Ken Croswell Earth and its planetary neighbors arose in a magnetic field strong enough to sculpt the disk of gas and dust that spawned our solar system and set the stage for a planet capable of developing life. That's the implication of new work that uses a meteorite to deduce the strength...

the unit h is referring to height or the Planck constant ze

In an attempt to determine how the temperature varies over a distance of 100m, I have taken five temperature measurements for every 10 meters, for a total of 55 measurements. I have then, for each dataset of N=5, calculated the mean value, standard deviation and standard error. Finally, I've...

In an attempt to determine how the temperature varies over a distance of 100m I have taken five temperature measurements for every 10 meters, for a total of 55 measurements. I have then, for each dataset of N=5, calculated the mean value, standard deviation and standard error. Finally, I've...

Question: hypothesis Would it be possible to determine/ capture the total wave function of an ensemble using quantum tomography & weak measurement ? As seen in the following article.. Its been done on a photon.. My question is, could this same technique be done on an ensemble of particles...

Homework Statement Hi, I am doing some basic X-ray analysis and trying to quantify the measurement uncertainty associated with my determined value for the K-α line of copper. I have obtained the x-ray spectrum from a copper target using a detector and multichannel analyzer (No. of pulses/pulse...

Hey guys, I've been learning about relativity recently and have a few thought experiments I'm pondering over. I'd appreciate input on the errors and validities of the consequences I've arrived at in my thoughts. The first thought experiment involves measurement of time. If we have an analog...

Many times, when I am driving my car, I worry about the tyre pressures. Why can't I have a gauge or friendly light to tell me they're ok? In my head, I have designed many different systems for the measurement and the telemetry. I realize it isn't 'very easy' but there's no reason it can't be...

For finding fan performance curve where better to put static pressure probes - near the surface or near the center of the duct ?

im hooking up 6 450v 10000uf capacitors in parallel for an exparement for school (under supervision of my professor) he won't tell me how to monitor these devices and how to know when they are full and when to release them. does anyone think they could give me a quick and dirty answer?