Measurement Definition and 1000 Threads

  1. B

    How measurement in the double slit experiment affects result

    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...
  2. R

    How to Estimate Expanded Uncertainty in Absolute Humidity Calculations?

    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...
  3. A

    Photometric and Radiometric measurement concepts

    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...
  4. Marc Nash

    Understanding the Dual Nature of Light: A Science Layman's Questions

    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...
  5. J

    Inductor's output power measurement using spectrum analyzer

    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...
  6. C

    First Measurement of the Ancient Solar System's Magnetic Field

    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...
  7. E

    What Does the Unit 'h' Represent in Measurements?

    the unit h is referring to height or the Planck constant ze
  8. G

    Can I Accurately Measure Temperature with 3 1/2 Digit Equipment?

    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...
  9. G

    How do I account for measurement uncertainties in temperature data analysis?

    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...
  10. C

    The No Cloning theorem vs weak measurement

    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...
  11. G

    Measurement uncertainty: Standard uncertainty of the mean

    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...
  12. R

    Exploring Relativity & Time Measurement

    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...
  13. sophiecentaur

    Remote motor tyre pressure measurement

    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...
  14. Y

    Measurement points for fan performance curve

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

    Measuring voltage and capacitance of capacitors in parallel? how do?

    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?
  16. A

    Why is force invariant in Newtonian mechanics?

    Recently, I've been pondering deeply on relativity (both Galilean and SR) and all of a sudden I find that I don't grasp even the basic concepts of physics (or life) anymore, i.e. I can't go back to my previous, "normal" mode of thinking. Consider Newtonian mechanics, take the ground to be at...
  17. ChrisVer

    How is the Rotational Velocity of Galaxies Measured?

    I was wondering, how can we measure the rotational velocity of a galaxy? In practice knowing the mass distributions and so on, we could calculate it by classical mechanics (or maybe GR). However people measured the rotational velocity of the galaxies and found that it doesn't correspond to the...
  18. Steven Ellet

    Can a Klein Tools Non-Contact Voltage Tester Measure Static Electricity?

    Would a Klein Tools Non-Contact Voltage Tester or similar be able to measure static electricity? If not what will? https://www.google.com/search?q=how...hop&q=Klein Tools Non-Contact Voltage Tester
  19. K

    EMF Radiation Measurement: 15 Milli Volts vs Milli Volts/Meter

    I measure the Electromagnetic Field Radiation at a point for example x distance from a source, and i am reading for ex. 15 milli volts per meter. Are these 15 millivolts per meter, equals to 15 milli volts ? I mean, if i do the opposite procedure, and receive a reading of 15 milli volts, at a...
  20. Quarlep

    Is there a definitive measurement in the universe?

    In Every measurement there must be uncertanity.In length or In time everything.Lets assume we have a ruler and a rope.If I measure the rope I get a result but I can't say this is exactly true because there's a unncertanity in measurement.Lets suppoe the rope is 100 cm minus or plus 0.5 mm.The...
  21. S

    Designing a Strain Gauge Load Cell: Q&A on Force Measurement

    Hello, I'm trying to design a strain gauge load cell for force measurments. I have few questions regarding that. Q1: how to calculate the minimum froce that my load cell can detect? Q2: how to calculate the FSO(full scale output) of my load cell? Q3: Is there any way to measure the...
  22. M

    Quantum Measurement Problem: Nature of Matter or Nature of Probability?

    The objective of this post is to: (i) generate a discussion of whether results of the double-slit experiment address solely the nature of matter, or do the results also address the nature of probability; and (ii) to determine if there have been any comparably structured experiments outside of...
  23. Y

    How Does a Vernier Caliper Determine Precise Measurements?

    I have made measurements using Vernier Calipers. What I don't understand about them is the coinciding thing. How does one know the value of the last digit of the measurement by seeing which marker of the main scale coincides with the Vernier scale?
  24. MathematicalPhysicist

    Does the intrepretation affect the measurement?

    The question is as in the title. I feel that it doesn't change the mausrement.
  25. R

    Measuring Torque of a Stepper Motor Using a Suspended Weight Method

    1. The problem statement, all variables and given/known data I am trying to experimentally measure the torque of a stepper motor at various velocities. I'm not quite sure how this should be done. Here is a diagram of my proposed method so far: Basically a weight is to be suspended from the...
  26. P

    Measurement of irradiance of 2 beam interference

    Hi, I have an experiment set up to get two beam interference fringes. I would like to know how I could measure the actual amplitude of the irradiance from the experiment. I have with me a power meter and a CMOS camera. How can I go about this? Thank you
  27. cosmik debris

    Weak measurement with post selection

    I'm reading stuff about weak measurements with post selection and its likely ability to improve computational performance. What I'm curious about is whether weak measurement is a real thing or not. There are many papers showing how to do the measurements and the theory behind them, and then...
  28. naima

    Quantum Measurement: Sharp vs Unsharp - How to Determine?

    How can we see if a quantum measurement is sharp or unsharp ? can we measure unsharpness? Thanks
  29. ChrisVer

    Errors in Measurement [of time]

    I wanted to ask something concerning the errors... Why sometimes the errors are taken to be \sqrt{N} where N is your measured value (such as the number of counts from a detector) and why is it sometimes given as half of your device precision (eg a common ruler's error is 0.5mm)? In my case I...
  30. T

    Hooke's Law- measurement of mass/weight

    A body of unknown mass hangs from a spring and stretches it to 50 cm. If the spring constant is 104 N/cm determine: a. the weight of the body b. the mass of the body k = mg/∆L W= Mg mass : k = mg/∆L 50/104= .4807692308 weight : W= Mg .4807692308*9.8=4.711538462
  31. V

    Measurement Theory - Quantum Mechanics Q&A by VVS

    Hey, I have a question about Measurement Theory. I am reading Quantum Mechanics by Ballentine chapter 9 Measurement and Interpretation of States. Please check the following pdf for my question: thank you VVS
  32. M

    Pressure Difference measurement using Pressure Sensors / Transducers

    Dear All, I am not sure if this is the right place or not for this post so i apologise in advance if not. I am trying to find some pressure sensors / transducers to measure the pressure difference (with respect to static pressure) at points on a circular cylinder model installed inside a...
  33. G

    Current measurement of a PM DC generator

    Hi, I'm trying to use a small PM DC motor as a generator to convert mechanical energy to electrical energy. I couple that small generator to another DC motor with spur gears and I measure the current of that small generator while it is driven by the DC motor at fixed speed. The circuit of...
  34. C

    Teaching Error in Measurement Lab

    Hello all, as a recent graduate and a new teacher, I am living in Honduras and teaching the sciences in a high school setting. I did not study to be a teaching by got my bachelors in Spanish and Physics. I am working at a bilingual school and my resources are extremely limited. My question is...
  35. V

    How to prepare sample for cyclic voltammetry measurement

    I am doing research on synthesis of copper nano particles. I would like to have a cyclic voltammetry (CV) of this material but I don't know how to prepare sample. Please tell me the ways to carry out this measurement. Thank you so much!
  36. A

    Comparing the variance of two samples with differing measurement error

    Homework Statement This is a statistics as applied to astronomy problem. My stats knowledge is horrible. Anyway, the problem: For several hundred objects, I have a number of different properties for which I have a measurement & associated measurement error. For example, flux density and...
  37. F

    Current Measurement of Incident Proton ?

    The proton current in cyclotron are normally measured by Faraday Cup. However, I do not understand that if there is target material for the proton beam. Proton is fully stopped in the target material, for example, water. How the current is measured if it did not hit anything else?
  38. K

    Measurement Problem & Objectivity

    I have never been to the pyramids in Egypt. I'd love to go one day. I am sure their configuration will be just as others have seen, and as the visitor map describes. Why is it that my experience will correspond exactly with others' experience if I am collapsing quantum potential with respect to...
  39. H

    Individual Measurement Uncertainty vs. Standard Error of Regression

    Let's say a student does a simple experiment where she conducts 10 trials at each x value (at each value of the independent variable). She collects data over 30 x values, giving her 300 total trials. For each of the 30 x values, she averages the 10 y values and she calculates the standard...
  40. C

    Frequency measurement -- how to choose sampling ?

    Hi, let's say I want to measure the frequency f of a periodic signal. I may take N data points with an arbitrary timestep of T. The question is how shall I choose T for a fixed N to have the best accuracy? In principle the frequency resolution is 1/(N*T) when taking the Fourier transform...
  41. F

    Time dilation measurement and events

    Hello Forum, An event is a point in spacetime with spatial coordinates and a time coordinate: (x,y,z,t). An event does not have a duration since it only lasts for an instant t. We can talk about time duration to mean the temporal separation between two different events, correct? In the...
  42. MikeGomez

    Measurement Possibilities: The Role of Efficiency and Distance in Bell's Theorem

    Quote from this recently posted article. http://www.nature.com/news/physics-bell-s-theorem-still-reverberates-1.15435 “Quantum theory does not predict the outcomes of a single experiment, but rather the statistics of possible outcomes.” My question is not in regards to the statistics of...
  43. J

    Measurement of relativistic effects from a non-inertial frame

    I was just thinking about this, and from a perspective of an inertial frame, it's easy to see how distances contract, times dilate, simultaneity varies between observer and the speed of light is exactly c in each case. But what about non-inertial frames? In the presence of gravity almost...
  44. O

    Measurement Uncertainty: How do I calculate it?

    Homework Statement Hey guys! I'm new here, so firstly- hello! I've a exercise to from Metrology. Evaluate measurement uncertainty for the following measurement: 1. Measurement quantity: length of a bar L = 500 mm 2. Material of the measuring object: steel 3. Temperature range in the...
  45. PeterDonis

    Modeling a measurement as unitary

    This question is inspired by reading Arnold Neumaier's article on Everett's measurement theory: http://arnold-neumaier.at/physfaq/topics/everett Suppose I have a system whose state lies in a two-dimensional Hilbert space, and I want to model a measurement of its state as a unitary evolution...
  46. N

    Uncertainty principle & simultaneous measurement

    I have been reading and would be interested in feedback to the comments that I make, below. One of the points made in this paper is that the interpretation of the uncertainty relation needs to be re-examined in its relation to the viability of having simultaneous measurements of A & B. For...
  47. M

    T type thermocouple for Delta T measurement

    I am working on an experiment where I need to measure the Delta T across a heat ex-changer. I have two independent T Type thermo couple, one at the inlet and the other at the outlet. Both tied to an Agilent data logger. I normally put the data into an excel sheet and generate Delta T = T1 - T2...
  48. nomadreid

    Measurement of singularity as a particle inside event horizon

    Although the subject line might seem to put this question inside general relativity, the reason I put it in quantum physics is because I would like to know what happens when one treats a singularity as a particle. Obviously from outside the event horizon, one cannot do this, but inside the event...
  49. S

    Pure state, mixed state and measurement

    Hello guys, Homework Statement the problem goes as follows: "Which measurement should you do on a statistical ensemble of qubits in order to distinguish between the pure state |Ψ>= cos(θ)|0> + sin(θ)|1> and the mixed state ρ=cos^2(θ)|0><0| + sin^2(θ)|1><1| " Homework Equations I am not...
  50. W

    Low volumetric flow rate measurement

    Hi everyone, I'm currently a mechanical engineer interning at an HVAC company. I need to measure the resistance of a fluid through ductwork. The CFD shows a linear curve through a plenum when plotting R vs volumetric flow rate. For example, a straight rectangular box 1 1/16” by 2.5” and 3ft...
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