05-28-2025, 08:39 AM
The main goal is not the result in itself but rather to make pupils/students/others aware of how we used to navigate, in addition to the fact that we have a magnetic inclination and that it changes. The procedure and showing what you can do with "simple" means are important ways to increase interest.
I am aware of the problems with systematic errors, but that is in itself an opportunity for discussing uncertainties in measurements. I let my students find the local inclination and declination using phyphox, and the results have a substantial spread so the discussion on why is interesting.
I did a quick test on finding the altitude and hour angle from the time and the position of the smartphone while aligning it to the sun, both with the method described in the sun trace experiment, and by fastening a drinking straw on the side of the smartphone. With this, I came within 6 degrees using the sun trace method and 3 degrees using the straw. So, finding the true north could be done.
NOAA has the app CrowdMag, https://www.ncei.noaa.gov/products/crowd...netic-data, which is used to collect data for finding magnetic anomalies, but it uses the World Magnetic Model to get the inclination. So, an experiment where one can get some indication, although uncertain, is interesting. At least we will work on it as a school open science project for next year's European Researchers' Night.
I finally resolved the problem, there was an extra <space> I didn't spot until I tried an online XML validator. So the project to collect SPL and frequency spectra will be implemented, with the use of a silent room calibration of the SPL at 40 dB. I will translate it into English and make it available as soon as I find some time.
I am aware of the problems with systematic errors, but that is in itself an opportunity for discussing uncertainties in measurements. I let my students find the local inclination and declination using phyphox, and the results have a substantial spread so the discussion on why is interesting.
I did a quick test on finding the altitude and hour angle from the time and the position of the smartphone while aligning it to the sun, both with the method described in the sun trace experiment, and by fastening a drinking straw on the side of the smartphone. With this, I came within 6 degrees using the sun trace method and 3 degrees using the straw. So, finding the true north could be done.
NOAA has the app CrowdMag, https://www.ncei.noaa.gov/products/crowd...netic-data, which is used to collect data for finding magnetic anomalies, but it uses the World Magnetic Model to get the inclination. So, an experiment where one can get some indication, although uncertain, is interesting. At least we will work on it as a school open science project for next year's European Researchers' Night.
I finally resolved the problem, there was an extra <space> I didn't spot until I tried an online XML validator. So the project to collect SPL and frequency spectra will be implemented, with the use of a silent room calibration of the SPL at 40 dB. I will translate it into English and make it available as soon as I find some time.