Doing physics means calculating a number by 
Ciro Santilli 35 Updated 2025-01-10 +Created 1970-01-01
Ciro Santilli 35 Updated 2025-01-10 +Created 1970-01-01In Physics, in order to test a theory, you must be able to extract a number from it.
It does not matter how, if it is exact, or numerical, or a message from God: a number has to come out of the formulas in the end, and you have to compare it with the experimental data.
Many theoretical physicists seem to forget this in their lectures, see also: Section "How to teach and learn physics".
Lecture notes:
- www.robots.ox.ac.uk/~az/lectures/ia/lect2.pdf Lecture 2: 2D Fourier transforms and applications by A. Zisserman (2014)
This mostly faceless German dude is awesome!
From Raw Crystal to Crystal oscillator
. Source. by United States Army Signal Corps (1943)Notably used to connect:
- pin headers
- breadboard holes
You can buy large sets of them in combitation of male/male, male/female, female/female. Male/male is perhaps the most important
Only certain battery voltages exist, because this voltage depends intrinsically on the battery's chemical composition.
learn.sparkfun.com/tutorials/battery-technologies/all (CC BY-SA) has a very good summary list, reordered from lowest to highest voltage:
| Battery Shape | Chemistry | Nominal Voltage | Rechargeable? |
|---|---|---|---|
| AA, AAA, C, D (Rechargeable) | NiMH or NiCd | 1.2V | Yes |
| AA, AAA, C, and D | Alkaline or Zinc-carbon | 1.5V | No |
| Coin Cell | Lithium | 3V | No |
| Silver Flat Pack | Lithium Polymer (LiPo) | 3.7V | Yes |
| 9V | Alkaline or Zinc-carbon | 9V | No |
| Car Battery | Six-cell lead acid | 12.6V | Yes |
Many/most microcontroller boards have analog-to-digital converters built into them, it is very convenient. E.g. it is the case for the Raspberry Pi Pico.
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