I like watching science videos on YouTube and I have a very basic understanding of electronics. But I never seem to get the “negative voltage” thing.
Why is it used and how does it differ from normal voltage.
In: 5
A voltage is a difference in electromagnetic potential between two-point.
The important part is that it is a difference. What is zero volts is up to you.
Take two AA batteries that each is at 1.5V and connect them in series. Call the point on the negative pole of the first battery as A. Between the two batteries as B and the end of the last as C like in the diagram below
A -====+ B -====+ C
If you define A as 0 volts then B is at 1.5vt and C is 3v.
If you define B as 0 volt then A is at -1.5V and C at 1.5V
If you define C as 0 volt the A is at -3V and B at -1.5V
Any calculation you make works the same regardless of what you define as 0V it is just a question of what is common and convenient to use.
For the power grid, you have the power plants connected to the physical earth and the same as your location, It is defined as zero volts so there is a common reference
If it is not any different elevation. You can define the floor on the ground level as 0 meters then level up the floor might be at +2meter but the cellar flor is at -2 meter.
Your zero point can be changed to the cellar floor than the ground floor is at 2 meter and the next at 4 meter.
The elevation is always relative to something just like voltage. Elevation can be considered as a difference in gravitational potential. If you ever have calculated potential energy as a function of elevation you have used elevation just as we use voltage
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