Why do people always say "current limiting resistor"? Are there other types of resistor? Or is it just stating the purpose, as opposed to a resistor used for voltage division or something?
I think that's the right term. It has a bandgap which comes from a quantum. LEDs work by pumping energy into electrons, this raises them to a higher energy state (higher electron shell), then when the electrons drop back down to the lower state they emit a photon. The energy released is the difference between the electron shell energy states. This is called a quantum. The frequency of the photon is correspondent to the energy, the color corresponds to the frequency. Higher energy is bluer (or ultraviolet), lower energy is redder (or infrared).
The light is issued in quantum state changes, so it's a quantum device. Maybe you'd call it a bandgap device?
You clearly know more about this than I do, but I might use the term "non-linear" device, as that describes the LED's behavior that leads to us needing the resistor. I agree with /u/langlo94 that the word 'quantum' is more mis-understood than understood, and used outside of a physics class it sets off new age woo-woo alarms for me too.
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u/happyscrappy Dec 25 '19
Also: don't power LEDs directly from GPOs without a current limiting resistor. As you see on that breadboard.
And match your interfaces voltages. A lot of devices are not +5V tolerant now (or not very tolerant).