More kinds of sensors and how do they work? What can you do with them?

I went through the rest of the sensors on Elfa. When I didn't understand what a sensor did or what you used it for, I just googled.

Redox-electrode from Elfa

What's a Redox-electrode?






 https://www.wikiwand.com/en/Redox
The link contained a beautiful gif of how it works on an atomic level:

Beautiful visualization from wikipedia

Reed-sensor

 

What's a Reed-sensor?


Youtube has the answer:

Current transformer? - Clip it on a cable and it senses how much current there is!
https://www.youtube.com/watch?v=IHozA4Ds5Ts

Thermo couple

Thermo couple? It measures temperature. It's just two welded wires?!?!
https://www.youtube.com/watch?v=rznBiteUy2A





Absolute encoder? -It measures angles using a beautiful disc with an important pattern.

Open it up and look inside:
https://www.youtube.com/watch?v=JwU_DrI_Mmc







I also looked at the standard motion sensor. It's pretty smartly done.

"If it's not made by card access, then somebody else made it"

 I don't know if you can call this market analysis? This is pretty fun.

I'm getting a hang on what you can do and what kind of problems you can easily solve with the electronics available.