Questions tagged [instrument]

A measurement instrument is a device used to sample physical observations. Examples include pressure sensors, thermocouples, etc.

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1answer
41 views

Is it possible to visualize water vapour with a low-cost instrument or setup in a lab? [closed]

Would infrared or laser be of any help? In a lab setting.
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42 views

Zero Error of Screw Gauge

Consider a screw gauge of 50 divisions on the circular scale. Till now I have used the following method to account for zero error in it. If $x^{th}$ division on the circular scale coincides with the ...
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1answer
56 views

Is there an instrument which can show the magnetic field in a region?

I know that an instrument called magnetometer exists. But it can only measure the magnetic field at a given point. I wonder if there exist, or is it possible to build a device which would be able to ...
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3answers
187 views

What is the smallest acceleration ever measured? [closed]

I'm having an argument (discussion) with a referee. I claim that the effects of expansion can be seen in local dynamics. That the orbit of Saturn is affected infinitesimally by the expansion of ...
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18 views

How is it possible to do spectral analysis of a light source?

I have a big book published many years ago by NASA which is page after page of numbers, the numbers being the irradiance of the sun at particular wavelengths. I wonder how such a book could be ...
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1answer
37 views

Is it possible to consider the oscilloscope as an essential instrument?

I recognize that the oscilloscope is a very useful instrument. But I would like to know what are the reasons why the oscilloscope is such a useful instrument in day-to-day scientific work. I would ...
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53 views

How does a Bourdon tube maintain constant volume?

I would like to understand why a Bourdon tube works, the working principle is described on wikipedia as: The Bourdon pressure gauge uses the principle that a flattened tube tends to straighten or ...
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2answers
156 views

What will happen if we try to take a voltage reading by keeping it in current mode in a multimeter?

There are different modes present in a multimeter. one is the current mode and voltage mode for their respective measurements. what will happen if one try to take a voltage reading by keeping it in ...
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52 views

When does the sensitivity of tangent galvanometer approaches a max value?

The image shows the approach of a few saying that the sensitivity is maximum if the deflection approaches zero. The white portion is a snap of a reference book which says the sensitivity is maximum if ...
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Least count of Vernier callipers

My teacher said the least count of a Vernier callipers with arbitrary MSD and VSD is equal to the highest common factor (of MSD,VSD). I have verified this with many cases ($VSD>MSD$, $VSD<MSD$) ...
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Identifying Physics Equipment

We are clearing out some old cupboards at school in our science department and have come across three different sets of physics equipment with no labels or instructions. Please could people kindly ...
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25 views

“Cooling down” a column thermometer

Typical medical thermometers based on a capillary mercury or fluid column expansion usually require employing centrifugal/acceleration methods to drive the fluid back to the bulb after performing a ...
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Is there an instrument that measures temperature (dynamic reading) at high irradiation doses?

I would like to measure the temperature in industrial gamma irradiation bunker. I know thermocouples are often used, but they only give max temperature reading, and I would like to have a dynamic ...
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Main scale reading and pitch of micrometer or a screw gauge

In a micrometer should the value of one main scale division be equal to the pitch? The measurements of the micrometer depend on the number on rotations and hence each rotation should be factored in. ...
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1answer
126 views

Accurate method or instrument to measure density of shaving cream foam or whipped cream foam?

I am currently filling a "standard" stainless steel cup of known volume with foam and then I weigh it. Then I calculate density. This method is pretty messy and I have to be careful about how I fill ...
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2answers
112 views

How can the apex angle of a Fresnel biprism be equal to $180^\circ$?

I am learning about Fresnel biprism. I wanted to know about biprism, and found out on the internet that it is a triangular prism with apex angle $180^\circ$. But I am unable to interpret $180^\circ$. ...
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234 views

Why do hot-wire instruments have a non-linear scale?

Hot-wire instruments are used to measure rms voltage or rms current in AC circuits. The construction of a hot-wire instrument is shown in the following diagram: Image source: Hitzdrahtmesswerk (Hot ...
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1answer
34 views

How does ultrasound imaging localize points in the $x$-$y$ plane?

Lots of sources describe how ultrasound imaging uses the time differences between wave emission and reception to calculate distances to points in the body. This makes sense for how localization works ...
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Probability that the Hubble space telescope hit by Meteoroids

What if Hubble Space Telescope or International Space State hit by micrometeoroid or meteoroid? Asking because these objects are moving at a very high velocity.
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How to decide the arrangement of an individual telescope in an astronomical interferometer?

Let's take the example of GMRT radio telescope, where individual telescopes are arranged in Y pattern. Please explain in detail.
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How the diffraction occurs in cassegrain telescope?

I know about the diffraction limit of a telescope. But please explain through diagram how diffraction occurs in Cassegrain telescope which has both primary as well as a secondary reflector.
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Why bulk of HPGe detectors is doped?

When I am looking at schematic diagrams of HPGe gamma spectrometer detectors (like this Ortec GLP one), it is often mentioned that bulk of Ge is doped. In this example - P-type doped. Is there a ...
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1answer
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Does a pipe hit at the top behave like an open-open system or an open-closed system?

I'm making an instrument out of an open-ended tube that produces sound when the top (opening) is struck. To find the lengths that correspond to pitches, I used V=λf and combined it with the ...
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1answer
95 views

What is spectral redshift resolution of observationally detected damped Lyman Alpha clouds?

What is the spectral resolution, $\Delta z,$ when detecting damped Lyman alpha systems at different epochs, $z \sim 0-3,$ through current and/or future observational instruments? And is this redshift ...
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416 views

Why is Fresnel Biprism a “Bi-” prism?

Why is the Fresnel Biprism made of two separate prisms joined together at their bases? Why not use a monoprism, a single prism having the same overall geometric and optical properties as that of the ...
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1answer
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Why is there no standardization of indentation hardness measurements? [closed]

The last hundred years have seen a great degree of standardization of units, and the expression of units of measurement in standardized, instrument-agnostic, objective terms. So I wonder why this ...
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Blackbody radiation source

I have an instrument in the lab which needs to be calibrated. Ideally, it needs to be calibrated using a device that produces near-perfect blackbodies called a "blackbody calibration source". An ...
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90 views

How to know that scientific instruments work?

While reading Zimring's book, What Science Is and How It Really Works, I came across some words on being skeptical about scientific instruments on p.183-184: "The extent to which such instruments ...
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156 views

Measuring small changes in length using the micrometer screw gauge

Which of the following method/instrument cannot be used to measure small changes of the order of a millimeter occurring in a length of about 50cm. 1)spherometer 2)travelling microscope 3)meter ...
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37 views

Measuring signal shorter than instrument response function

If one has a well-defined instrument response function (IRF) of some known full-width half maximum (FWHM), and they are measuring a signal that is shorter (but the shape is known), is it possible to ...
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32 views

Why infrared laser goggle looked orange?

So here's the thing, the laser goggle for UV light looked orange-yellow, which was sort of understandable, cause, if one want to block UV light, then the transmitted light ought to stay away from the ...
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1answer
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Why do pipe organ tubes need to have different thicknesses?

In a pipe organ, there are many tubes—long and short, thick and narrow. Each tube presumably resonates at a specific frequency based on its length and produces a distinct note. Why do they have to be ...
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43 views

Digital Tachometer

How actually does a Non-Contact Type Digital Tachometer work? The answer which I could find is - The infrared light from them tachometer falls on the surface and gets reflected back to the ...
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1answer
54 views

Clarification on the three omega method for measuring thermal conductivity

I've recently come across the $3\omega$-method for measuring thermal conductivity in materials. Now I'm told that we use a lock-in amplifier to measure the 3rd harmonic in the voltage across the metal ...
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1answer
154 views

How do I find out the tension and the weight of a string with a given frequency?

I'm trying to build my own string instrument. I can make the string however long I want it to be, the instrument should play a B which is at 493.9Hz. What calculations do I need to do?
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49 views

Plasma Waves at Different Frequencies

I am trying to determine what plasma waves appear at what frequency ranges. Particularly, I am interested in exploring plasma waves occurring between 100kHz to 1MHz. Is this a bad frequency range to ...
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Please help identify this physics apparatus!

This was my grandfather’s and have no idea what it is only that it is some piece of physics equipment! The main black cylinder doesn’t seem like it wants to rotate but not sure if it should?
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2answers
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What is the difference between a galvanometer, an ammeter and a voltmeter?

I'm looking for basic differences b/w the three with respect to nature of the circuit as well i.e either it is connected in parallel or series, and also the reason as to why they're connected the way ...
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79 views

Is Potentiometer a variable resistor or a measuring instrument?

I have used Potentiometers many times, and what I understood is that it is a variable resistor. However, my Physics teacher says that he is SURE a potentiometer is used to measure stuff, and is NOT a ...
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1answer
533 views

The Geiger Counter

In my class, we talked about the GM-counter and we were shown a graph with the voltage on the x-axis and intensity on the y-axis. But I do not understand why the graph has the characteristics it has, ...
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5answers
120 views

Is there such a thing as a work meter to measure work?

I know there are devices to measure power (e.g., dynamometers) but I can't think of any example of a device that measures work directly. Is there such a thing?
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3answers
77 views

Manometer physics? How to keep nozzles from draining?

Picture two liquid spray nozzles spaced vertically by some distance. Both nozzles are connected via flexible tubing to a single valve via a tee. Once the nozzle lines are full of fluid how can i ...
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1answer
943 views

What's the longest wavelength single photon we've ever observed? [duplicate]

At short wavelengths, our light detectors tend to be photon counters (e.g. CCD light sensor). At longer wavelengths, we use antennas and bolometers that tend to add up energy instead of counting ...
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38 views

How to devise a microwave power sensor?

I am fairly aware of the general thermistor/ diode/ thermocouple methods of sensing microwave power. Currently my requirements are simpler: A device that senses only microwave power incident on it - ...
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1answer
181 views

Effect of Lock-in Amplifier Phase Noise

Suppose that an oscillator with phase noise is used to drive a modulating process and that the same oscillator is used (with an appropriate phase shift) is used to synchronously demodulate the signal ...
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2answers
71 views

How should a hydrometer be read?

Probably due to surface tension the surface tends to curve near the hydrometer forming a meniscus. The question is whether it's correct to read the hydrometer at top of the meniscus or at the liquid ...
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1answer
58 views

How can the color of the sun be measured?

As the sun sets it changes color, sometimes first becoming orange, then red, for example. The device typically used to measure color is a colorimeter, but all of the colorimeters I have seen only ...
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1answer
300 views

How can I calculate the sensitivity of a seismometer?

I would like to know how to find the minimum ground motion a seismometer can measure, specifically if a certain seismometer can measure 1 micron/sec velocity. I have a few specs from the datasheet but ...
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1answer
485 views

What does a retarding field energy analyzer measure?

According to [1], p.58, the current collected by a retarding field analyzer is: $$I= qA \int^\infty_{v_{min}} vf(v)dv $$ where $q$ is the electron charge magnitude (here singly charged ions are ...
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1answer
36 views

Calibration of LCD display type thermometer (without extended probes)

How can we ensure correctness of an LCD display type thermometer used indoor e.g. the HTC-1 which does not have extended probes.