Questions tagged [measurements]

Measurements, instrumentation, calibration and metrology.

Filter by
Sorted by
Tagged with
3
votes
3answers
16k views

How much current is this phone drawing?

I know the current should be higher than 0.67 mA, because I know phones use current in the order of 1A. Also the charger is able to support up to 1A, it doesn't make sense that the charger would have ...
5
votes
1answer
131 views

How does an ultrasound device determine where the reflection is coming from?

When the ultrasound transducer emits a signal and the signal comes back to the receiver how does the software or hardware determine where it came from? I understand it finds distance or depth by delay....
3
votes
2answers
248 views

Measure the distance to a balsa wood strip with 1 mm accuracy

I am working on a project where I need to determine the density of a balsa wood strip. I know the length and height of the strip. The two measures left to take are the weight and the thickness of ...
14
votes
3answers
5k views

Can I use a ultrasound sensor to measure water level?

If I use an ultrasonic sensor will it detect the water level? I was thinking about a product to read water level on water boxes (common in Brazil). I researched about instrumentation for this ...
11
votes
6answers
13k views

Distance sensors with accuracy of 1 mm?

I am making a device for measurements. I would like to measure the distance within accuracy of 1 mm. Range could be 2 cm to 15 cm . I looked at Proximity Sensors but the readings displayed by these ...
3
votes
1answer
2k views

Building laser interferometer from CD/DVD drives parts

Is it possible to build interferometer, for linear displacement measurements, using old CD/DVD drive parts? I am talking about using parts such as beam-splitter, detector, laser and frame where it ...
11
votes
5answers
3k views

Practical setup to measure angular velocity

I have got a spinning top from a Canadian manufacturer, and I am deeply amazed by how neatly it spins. My interest in physics has led me to try to find out at what top speed I can spin the top and ...
2
votes
1answer
378 views

Dead weight pressure tester for very low positive pressures

Does the dead weight tester technology provide capability for an accurate, low pressure calibration standard in the range of zero to 150 cm H2O, and if so is there a manufacturer that provides such an ...
5
votes
1answer
468 views

LabView or another software for experiments [closed]

I used LabView for a lot of my BME undergrad, but the labs focused mainly on things dealing electrical signals. In the real world I'm working mostly on ME projects, but we lack a good deal of ...
7
votes
5answers
1k views

What was that?! Quantifying the impact of a martial arts strike

Measuring things like a martial artist's strike can be challenging because it is a complex motion and common vernacular will use imprecise or incorrect terms. This question is an attempt to identify ...
28
votes
10answers
6k views

How to quantify martial arts strikes?

Subtitled: Ah, strong am I with the Force, but how do I measure it? With all due apologies for paraphrasing Yoda, I am trying to measure a force. Fortunately, it's an easier force to measure than ...
13
votes
2answers
8k views

How does a multimeter protect itself from high voltages?

I have used a cheap multimeter to measure voltages in simple DC circuits, but I have seen pictures of them plugged straight into the mains and used to measure various home-built generators. Why doesn'...
5
votes
1answer
138 views

Question about "uncertainty"

I'm a bit confused about all the different "definitions" of uncertainty? One can calculate "uncertainty" of a single measurement by simply checking how accurate the tool that is being used to do the ...
13
votes
3answers
5k views

Measuring longer distances with high accuracy

I am involved right now in the fabrication of steel structures on the order of 5-50 feet long. Presently, we measure these structures with garden variety commercial tape measures. Most of the time, we ...
10
votes
2answers
534 views

How is gas flow through (extremely long) pipelines monitored and controlled?

(This is closely linked with measuring the Mach number inside a nozzle but it is not regarding the supersonic flow) Friction and heat transfer have effects on the Mach number of the compressible flow ...
22
votes
3answers
1k views

How to know whether the flow is supersonic in a nozzle?

For a project I had built a convergent divergent nozzle designed for Mach number = 3. In that project, I could know the flow has gone supersonic by seeing the manometer fixed between the throat and ...
17
votes
3answers
4k views

How does measurement uncertainty combine with tolerances?

Given a tolerance within which your workpiece should be manufactured, say some length should be $10\pm1$mm. If you determine that your uncertainty in measuring this length is $0.2$mm (at 95%). How ...

1 2 3 4
5