What is Measuring: Definition and 1000 Discussions

Measurement is the quantification of attributes of an object or event, which can be used to compare with other objects or events. The scope and application of measurement are dependent on the context and discipline. In natural sciences and engineering, measurements do not apply to nominal properties of objects or events, which is consistent with the guidelines of the International vocabulary of metrology published by the International Bureau of Weights and Measures. However, in other fields such as statistics as well as the social and behavioural sciences, measurements can have multiple levels, which would include nominal, ordinal, interval and ratio scales.Measurement is a cornerstone of trade, science, technology and quantitative research in many disciplines. Historically, many measurement systems existed for the varied fields of human existence to facilitate comparisons in these fields. Often these were achieved by local agreements between trading partners or collaborators. Since the 18th century, developments progressed towards unifying, widely accepted standards that resulted in the modern International System of Units (SI). This system reduces all physical measurements to a mathematical combination of seven base units. The science of measurement is pursued in the field of metrology.

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  1. P

    Measuring the Resistance of a Wire

    Hi, First and foremost, I hope this question doesn't sound stupid! I am doing a lab for school in which I have to measure the resistance of a wire. As part of that, I have to measure the p.d across the wire and the current through it. After collecting my results my teacher said that I...
  2. F

    Exam: Measuring the Coefficient of Friction

    Hi everybody. I am going to exam on Monday. I would like to make a experiment on how to measure the coefficient of friction. I know, that I can find the mu(s), by taking the tan to the angle α. μs = tan(α). Is there somebody, who has some others ideas how to measure that? Somebody...
  3. L

    Measuring BJT DC Operating Point

    Hey guys, I am working on my lab with BJT with a Common Emitter Configuration. One of the steps asks me to measure the DC Operating Point, however I am not sure what they want. What I think they want is for us to find the point VCE where the slope of the collector current vs VCE intersects...
  4. A

    Measuring sound velocity from a P-T graph?

    I don't have any specific numerical values for this, as it's a general question, but hopefully I explain it well enough using only words: If you plot a graph of position vs. flight time (of a sound pulse, for example), what is the slope of that graph going to be? (That is, what does the slope...
  5. V

    Is Heisenberg uncertainty principle a problem of our measuring techniques?

    Hello I know this topic must have been done to death already, but i can't seem to find a satisfying answer. As the title suggests, my question is, what experiment proves that the uncertainty principle is not just a result of our flawed measuring techniques? From what i understand, when we...
  6. S

    How do I measure the distance of a galaxy using conventional terms?

    Expressing the cosmological distances with conventional terms is very confusing. For instance, if we say that "a galaxy is a 1 billion light years away" what this is really mean? 1. If all moves stopped (moves in space and expansion) the light will travel from that galaxy (center of it) and us...
  7. R

    Value of a measuring rod in an expanding universe?

    I have a question, but I'm a neophyte so please correct my premise if it is wrong. If it is true that in an expanding universe the space between any 2 points increases than wouldn't it be true that the space between the end points of a measuring rod (e.g. a light year, or more fundamentally a...
  8. P

    Stellar Astronomy - Measuring surface temp of the Sun

    Homework Statement "Determine a surface temperature value for the Sun from the angular diameter of the Sun and the solar constant." Homework Equations L=4π(R^2)σT^4 The Attempt at a Solution At this point my only stumbling block is I don't understand the relationship between the solar...
  9. P

    Measuring Electrical Potential and Electrical Fields without a computer

    Hey physics forums I was kind of curious if there how people measured electric field and of course guass's law before we had computers, so I talked to one of my professors about it. He told me that a long time ago people used something involving plates and soap bubbles to prove that guass's...
  10. J

    Question about Experimentally Measuring Mass

    In an experiment that I conducted, I was instructed to measure the mass of a substance (NaCl) in it's container BEFORE measuring the mass of just the container. Is there a logical reason behind doing it in this order rather than measuring the mass of the container FIRST AND THEN measuring...
  11. A

    Measuring Water Flow From an Elevated Bottle: Physics in Action!

    If I do an experiment where I want to work out how fast a certain amount of water will empty from an ordinary plastic bottle elevated greater than horizontal, what Physics could I apply if I measure the angle at which it is emptied, the height above the ground and how long it took to empty. I...
  12. O

    Measuring Friction on a Sloping Track

    1. I need to set up a lab. The goal is to find the force of friction between a track and a ball. The track is flexible and tilted so that it slopes down. Looking at it from the side, the track looks like half of a U. The ball is released from the top of the track and somehow I have to figure out...
  13. N

    Why/how does energy change when measuring position?

    Hello, As a concrete model to refer to, I'll work with the one-particle system in a potential box with infinite edges. Inside the box is a potential barrier of height V. Let's say we've measured the energy at one moment to be E < V. The probability of measuring the particle inside the barrier...
  14. L

    Measuring Electric & Magnetic Fields: Uncovering the Mystery of Gauge Potential

    In electrodynamics, the gauge potentials are not directly measureable, but components of the field strength tensors, which are the electric and magnetic fields are. But why are the electric and magnetic fields, the components of the curl of something not-measureable (the gauge fields)...
  15. M

    Measuring the phase in neutrino oscillations

    Hi, When we talk about neutrino oscillations, the discussion is always about the phase that a particular flavour eigenstate picks up with time. The phase is usually partly geometric and partly dynamic. I have a question about this. How do we measure the phase experimentally? What is the...
  16. R

    Measuring blood pressure in a non-electric way

    Homework Statement I have to conceptually design a device that works with a sphygmomanometer but does not need the stethoscope. So it needs to function with the oscillatory method (analyzing the signal of pressure changes as heart pumps blood as opposed to listening to the Kirchoff's sounds)...
  17. Spinnor

    Measuring Neutrino Oscillations in a Solar Neutrino Rest Frame

    If I moved in the rest frame of a solar neutrino would I still measure neutrino oscillations? Thank you for any help!
  18. Q

    Rocket-man measuring speed of light

    Suppose a rocket is traveling almost at the speed of light...but relativity says he will still measure the speed of light 3*10^8...if a beam of light is sent at the time the rocket started...if the beam of light and the rocket both travel the same distance, let 2 light minutes, then what will...
  19. K

    Measuring 3 phase power current

    Hi there all I'm looking to measure current in 3 phase cables, and would like some advice on any current clamp models you'd like to recommend. However, I'm not entirely certain on the method as well; I've used current clamps before on single phase cables, and I'm aware that you need to clamp...
  20. S

    Measuring the temperature of a combustion

    I am not 100% certain this is the best place for this. Moderators, if you think a different board would be better, please relocate this. Anyway... I am wanting to measure the peak temperatures of my combustions of hydrogen. I got to thinking, "If I am using air as the source of oxygen, then...
  21. P

    Measuring Efficiency of Fuels with Physics, Chemistry and Biology

    Hi, I am working on this project that has to involve physics, chemistry and biology. The chemists in my group will be performing an experiment to measure the enthalpy of combustion of three different fuels: alcohol, diesel and petrol. My task as a physicist is to, using their results...
  22. S

    Measuring Charge Of An Aerosol

    Hi, I was wondering how I would go about measuring the electrical charge of an aerosol (A sodium chloride aerosol generated using a compressed air type nebulizer and dried using compressed at approximately 100 l/min flow) I have seen Faraday cup used for such measurement but was hoping for...
  23. G

    Is Time Measurement Unidirectional and Irreversible?

    I asked this in another thread but I may have been off topic.. I'm not quite sure which thread to ask in.. I was wondering if it is okay to say that you can measure an inch in any direction but you can only measure time in one direction. And if, in the same vein, is it okay to say that you...
  24. M

    Measuring Bond Angles in Molecules

    How can the bond angle in a molecules are measured ? The methods used to measure the angles and length b/w bonds.
  25. W

    Measuring mass without a balance

    Homework Statement You are to design, build and test a method to accurately measure the mass of an object. You cannot directly weigh the object but must use experimental data to determine your result. You cannot build any type of spring balance or beam balance. You are to determine your method...
  26. D

    The Spaceship experiment: Questions on Light's Inertia and Measuring Distance

    Hello. Some years ago I came across an animated illustration of relativity, housed in what seems to be a classic use of a bouncing light within a spaceship. (Similar to that found in http://galileoandeinstein.physics.virginia.edu/lectures/srelwhat.html.) My education in physics is limited to...
  27. B

    Measuring Resistance: Bridge Deck Steel Bars & Wire

    Hello, I had to measure the resistance between different sets of bridge deck reinforcement steel bars using a Wavetek HD110T multimeter and a wire. The values varied between 1.9 to 2.8 ohms. When I measured the resistance of the wire itself, it came out to be 2.1 ohm. I could not...
  28. G

    Measuring Inductance Value of Handmade Inductor

    Hi all! I tried to make an inductor. Naturally, I am not sure about it's inductance value. I made an LC series circuit on a bread board. I am using a oscilloscope and an a function generator to find the value of L during the resonant frequency. Channel one goes from function generator...
  29. E

    Measuring a loudspeaker's diaphragm

    Hi all, First of all, thank u for ur time and sorry about my english. I have measured a loudspeaker's Sound Pressure Level from a distance of 1 m. At the same time, I've measured, with a accelerometer, the displacement, velocity and acceleration of the loudspeaker's diaphragm. I've found...
  30. A

    Observers and Measuring Devices

    Just wondering if anyone can explain to me why it is thought necessary to say that consciousness (an observer) is necessary to account for certain things in Quantum Physics (e.g. for the collapse of the wavefunction), rather than just say that a measuring device (with or without a conscious...
  31. T

    Why is the probability of measuring an eigenvalue its coefficient squared?

    Homework Statement This is an example from Gasiorowicz's Quantum Physics. "Example 3-1" is a particle in an infinite potential-well, but that should not matter. Homework Equations The Attempt at a Solution Why is P(-2) (which I suppose is the probability that the eigenvalue -2 is...
  32. I

    Measuring gravitational force of the Earth

    Hello, our teacher told us that how could we find the gravitational force of the Earth, and i wanted to do it with falling objects (Only option i got, no pendulums). Does anyone have an idea what is a free-fall apparatus? I wanted to measure it just with a cronometer, but i need more precise...
  33. J

    Medical Measuring Venous Pressure to 5mm Hg

    hi the venous pressure is typically about 5mm Hg describe a method to measure this pressure
  34. N

    Measuring the Optical Power of a Pulsed Source

    Hi. I was wondering if someone can provide me with some advice on the proper way for measuring the optical power of a pulsed laser system? My optional methods are: - Photodiode detector: measuring average power - Oscilliscope with optic-electric converter...
  35. J

    How Can We Calculate the Acceleration of Gravity Using Time Measurements?

    The acceleration of gravity can be measured by throwing an object upward and measuring the time that it takes to pass two given points in both directions. Show that the time it takes the object to pass a horizontal line A in both directions is Ta, and the time to pass a second line B in both...
  36. T

    Measuring flow through a balancing valve

    My company installed a number of balancing valves (Tour & Andersson, STAD) in a central heating system. These valves are used to measure the flow (in this case water). According to the valve's specs it should be installed with a certain distance of straight pipe both before and after the valve...
  37. M

    Measuring Wetness/Spotting/Filming

    Hi everyone, I was wondering if anyone knew of any test methods to quantitatively measure any of the following three things: (Note: These aren't theoretical questions, I am looking for tangible laboratory solutions to these problems) Wetness Suppose you have a collection of several...
  38. E

    Measuring the size of a molecule

    Hi, Homework Statement I am trying to determine the size of a molecule..by doing the oil drop experiment where we drop a tiny droplet of oil on water covered with a thin layer of powder...and then make calculations based on the diameter of the circle... the droplet forms in oil. The Attempt...
  39. B

    Determining concentration by measuring pressure change

    Homework Statement Derive an equation how one can calculate concentration by measuring pressure change in a known volume. Known data: Pressure change dp/dt in a known volume V, volumetric flow rate F, total pressure p and temperature T. Homework Equations Probably ideal gas law...
  40. E

    Measuring speed of sound in air

    Hi. I have been given the task to measure the speed of sound in air. The materials available are: 1. Microphone 2. Signal Generator 3. Amplifier 4. Digital Oscilloscope I have looked through google and the simplest exp involves a loudspeaker as well. However I don't have one...
  41. V

    Measuring Energy of Transients in electrical circuits

    Hi, Is there a way or reasonably priced equipment out there that can measure the energy levels of transients in electrical circuits? Any help would be appriciated!
  42. L

    Measuring current on a loop without a conventional source

    Greetings, I have a problem that's been bugging me for a few days now. I've asked electrical engineers, students and graduates, and I can't seem to find a clear-cut answer to these questions. THE SCENARIO One piece of copper wire has one end connceted to a terminal from a multimeter...
  43. S

    Conceptual question on measuring momentum of a particle

    Just a very conceptual question about measuring momentum of a particle: first off, when we measure the position of a particles by say, firing a photon at it, its wave function collapses to a spike at the point where the particles was seen.. If we measure the momentum of a particle, its wave...
  44. J

    Measuring the force of a punch

    Hello, I am trying to help a student set up an experiment in which he needs to measure the force of a punch. Any suggestions on what equipment/sensor I can use to do this? Thanks! Jessie
  45. P

    Measuring the period of a pendulum or spring with a stopwatch

    Homework Statement For the pendulum or spring and mass system at your station measure the period with a stopwatch Homework Equations The Attempt at a Solution So a period of a pendulum is when it returns to its original position after passing equilibrium twice. So I would...
  46. H

    Homodyne Detection and measuring quadratures

    Hello Can anyone explain to me what measuring quadratures are in relation to homodyne detection? Thanks
  47. L

    Measuring Viscosity of Ferrofluid: A Beginner's Guide

    Homework Statement I have a fluid dynamics question and I am hoping maybe you can help me with it. I haven't taken a fluids course yet so I am at a loss as to the solution, and all of the books I've looked through have left me empty handed. For my Experimental project i decided to measure the...
  48. S

    Coordinate system transform for antenna measuring system

    Hello, I have a question related to coordinate transform. If this is not the right section please feel free to move this thread. My problem is the following: I have a positioning system to move an antenna, that allows me to perform scans according to a great circle coordinate system. Check...
  49. B

    Probability of measuring the ground state of a particle (quantum mechanics)

    Have to find the probability of measureing the ground-state energy of a particle. -in infinite potential well 0<x< a has wave-function \psi (x,0) = Ax(a-x) where a is the (known) length of the well, and the norm. const. A has already been found. The eigenvalues of the hamiltonian in...
  50. A

    Measuring Parallax Angle to the Method

    I have read the parallax method of determining large distances and i do understand it. I agree it is easy to find the distance of the basis(distance between two observation points) but how do they measure the parallax angle?
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