I am reading up on logic circuits, families and levels because it's fun. I have no formal education in physics, computing or electronics.
For power supplies, sometimes one of the supply rails is referred to as ground (abbreviated "GND") โ positive and negative voltages are relative to the ground. In digital electronics, negative voltages are seldom present, and the ground nearly always is the lowest voltage level. In analog electronics (e.g. an audio power amplifier) the ground can be a voltage level between the most positive and most negative voltage level.
I know from previous reading, that electricity - at least when it comes to direct current, but perhaps even when it comes to AC? - has a way in ("line"?) and a way out ("neutral" or "ground"? - disregarding for a second the fact that ground also carries current in case of a ground fault).
Again, from previous reading, I know that we work computers by either supplying them voltage or not (or in some circuits a higher voltage and a lower voltage). In any case, it's a choice between one or the other, since that is what we are trying to represent: boolean true or false.
So, what is this "negative voltage"? Is this a figure of speech or can voltage actually have a negative value? The part from the article that I quoted above states in relativistic terms, that "the ground can be a voltage level between the most positive and most negative voltage level" (italic text by me), which makes me assume "yes". But if voltage is electromotive force, how can it be negative? I amusingly imagine a force "sucking" the current backwards. ๐คญ
Explain it to me as if I was five. ๐ถ
This makes me realize how mind blowing the technology is: if I assume correctly, we have electromagnets inside the speaker that can alternate between the two potentials at the same frequency/speed as is required for the tone in question? And that's just only one tone. Holy shit... how many times per second do the electromagnets turn on and off in order to create sounds that we recognize as music?!
If you want to know something else mind blowing, you can actually use a speaker as a (very shitty) microphone! The same principle of moving the cone by applying a voltage works in reverse: if you move the cone you will create a voltage. And since sound is nothing but moving air, talking into a speaker cone will create a voltage in relation to the sound.
Thats the sidenote on my previous comment!
Oh for sure, there's a famous quote that goes along the lines of "Technology at a certain point to the average person is indistinguishable from magic"
Right on the money! For subwoofers they're huge cones and huge magnets (I LOVE the pressure of an 18" super scooper), those go at 15-150 times a second back and forth. For your phone speakers or earphones they've the tiniest membranes that go at 200-18000 times per second. A quality soundsystem will combine these to get a range from 20-22000Hz which is a little more than our ears ability.