ME 11: Measurement and Instrumentation

Proof required

Link the public repo with the worked examples in Annex H of the GUM, redone on your own before you read each answer written up (a typeset PDF, LaTeX source or notebook), and show the self-check: which answers matched and how you fixed the ones that did not.

What gets checked

• Type A and Type B uncertainties are separated, then combined with sensitivity coefficients (in quadrature when the inputs are independent).
• Every result is reported with its expanded uncertainty and coverage factor.
• Each answer matches the GUM's own numbers, and misses are reworked.

Common mistakes

• Answers copied from a solution with no working.
• Missing units, or a free-body diagram or sign convention left out.

Powstik Guide

A public write-up of the worked examples in Annex H of the GUM, redone on your own before you read each answer, with the self-check shown.

Steps

1. Study the linked course material.
2. Solve the problems on your own first.
3. Check them against the self-check and rework the misses.
4. Typeset the write-up (LaTeX or a notebook) in a public repo.
5. Ask someone who knows the subject to check it.

README
ME 11: Measurement and Instrumentation, unit 1: Measurement error, statistics and uncertainty
Problems:
Self-check result (matched / reworked):
What I got wrong first and why:

What gets sent back

• No working shown.
• The self-check result is missing.

Resources

What a verifier looks for

• Type A and Type B uncertainties are separated, then combined with sensitivity coefficients (in quadrature when the inputs are independent).
• Every result is reported with its expanded uncertainty and coverage factor.
• Each answer matches the GUM's own numbers, and misses are reworked.
• Is the engineering right, not just the final number?

You'll sign in first, then come straight back here.

Proof required

Link the public repo with strain-gauge bridge, thermocouple and amplifier problems from the NPTEL lectures, each checked by building the circuit in CircuitJS written up (a typeset PDF, LaTeX source or notebook), and show the self-check: which answers matched and how you fixed the ones that did not.

What gets checked

• Bridge outputs are found for quarter-, half- and full-bridge layouts.
• Each sensor's sensitivity and range are stated with units.
• Every hand answer is shown next to the simulated value, and gaps are explained.

Common mistakes

• Answers copied from a solution with no working.
• Missing units, or a free-body diagram or sign convention left out.

Powstik Guide

A public write-up of strain-gauge bridge, thermocouple and amplifier problems from the NPTEL lectures, each checked by building the circuit in CircuitJS, with the self-check shown.

Steps

1. Study the linked course material.
2. Solve the problems on your own first.
3. Check them against the self-check and rework the misses.
4. Typeset the write-up (LaTeX or a notebook) in a public repo.
5. Ask someone who knows the subject to check it.

README
ME 11: Measurement and Instrumentation, unit 2: Sensors and signal conditioning
Problems:
Self-check result (matched / reworked):
What I got wrong first and why:

What gets sent back

• No working shown.
• The self-check result is missing.

Resources

What a verifier looks for

• Bridge outputs are found for quarter-, half- and full-bridge layouts.
• Each sensor's sensitivity and range are stated with units.
• Every hand answer is shown next to the simulated value, and gaps are explained.
• Is the engineering right, not just the final number?

You'll sign in first, then come straight back here.

Proof required

Link the public repo with three phyphox measurements of known values (g at rest, a pendulum period, a reference tone), each with a calibration and an uncertainty written up (a typeset PDF, LaTeX source or notebook), and show the self-check: which answers matched and how you fixed the ones that did not.

What gets checked

• The sampling rate is stated and shown to avoid aliasing.
• The accelerometer is calibrated by resting the phone on each of its six faces, giving an offset and a gain per axis with uncertainties.
• Each measurement is compared with its known value, and the difference is inside the uncertainty or explained.

Common mistakes

• Answers copied from a solution with no working.
• Missing units, or a free-body diagram or sign convention left out.

Powstik Guide

A public write-up of three phyphox measurements of known values (g at rest, a pendulum period, a reference tone), each with a calibration and an uncertainty, with the self-check shown.

Steps

1. Study the linked course material.
2. Solve the problems on your own first.
3. Check them against the self-check and rework the misses.
4. Typeset the write-up (LaTeX or a notebook) in a public repo.
5. Ask someone who knows the subject to check it.

README
ME 11: Measurement and Instrumentation, unit 3: Sampling, data acquisition and calibration
Problems:
Self-check result (matched / reworked):
What I got wrong first and why:

What gets sent back

• No working shown.
• The self-check result is missing.

Resources

What a verifier looks for

• The sampling rate is stated and shown to avoid aliasing.
• The accelerometer is calibrated by resting the phone on each of its six faces, giving an offset and a gain per axis with uncertainties.
• Each measurement is compared with its known value, and the difference is inside the uncertainty or explained.
• Is the engineering right, not just the final number?

You'll sign in first, then come straight back here.

Proof required

Link the public repo with the raw data (or links to it), photos of the set-up, the analysis notebook and the predicted-vs-measured table with uncertainties (under 18 without an adult: a simulation of the same set-up, compared with published values), and a README that says how to rerun it and what limits the result.

What gets checked

• Three uncertainty budgets in the GUM's form are in the repo, with the raw data.
• Each result is reported as value ± expanded uncertainty (k = 2) and compared with the local g.
• The write-up says which input dominates each budget and how to reduce it.

Common mistakes

• A result that nobody else can rerun from the repo.
• A table with no explanation of the gaps.

Powstik Guide

A measured experiment that finds the acceleration due to gravity three ways with your phone: the accelerometer at rest, a pendulum's period, and a small ball (never the phone) dropped from a measured height and timed with phyphox's acoustic stopwatch, in a public repo.

Steps

1. Write down what you expect before you start.
2. For each method, write the measurement equation and an uncertainty budget in the GUM's form (each input, its standard uncertainty, its sensitivity coefficient). For the drop, start the timer with a sharp sound at release, such as two coins struck as you let go, and stop it with the landing sound. Include the release-timing and sound-travel delays in that budget. Take at least ten readings per method. Compare all three with your local g from a published gravity model. Say which method is best and why, from the budgets.
3. Fill the predicted-vs-measured (or hand-vs-simulated) table.
4. Explain every gap with a cause someone can check.
5. Write the README and ask someone who knows the subject to check it.

README
ME 11: Measurement and Instrumentation — Measure g three ways, with full uncertainty budgets
What I expected:
How to rerun it:
Predicted vs measured:
Why they differ:
Safety: hand tools and eye protection only

What gets sent back

• No predicted-vs-measured table, or no uncertainties.
• Machine tools, welding, pressure vessels, combustion, or springs and flywheels storing dangerous energy without a trained supervisor.

Resources

What a verifier looks for

• Three uncertainty budgets in the GUM's form are in the repo, with the raw data.
• Each result is reported as value ± expanded uncertainty (k = 2) and compared with the local g.
• The write-up says which input dominates each budget and how to reduce it.
• Check the engineering and the numbers, not just that it exists: do the units, the hand calculation and the table agree?
• Build photos show hand tools only and eye protection worn: no machine tools, welding, pressure vessels, combustion, or springs and flywheels storing dangerous energy (unless a trained supervisor and a proper workshop are shown).

You'll sign in first, then come straight back here.