Can 2 different voltages share a ground?
It is OK to use one ground with the voltage regulator circuit as you have shown. In fact, I don’t think it will work if the 12V source and regulator are referenced to separate grounds.
Why do you have to ground a circuit?
Grounding helps protect you and your home from the dangers of damaged circuits or electrical overloads. When power surges happen, the excess electricity introduced to the system could leap out of the wiring. Without electrical grounding, this stray voltage could start a fire, damage appliances, or shock bystanders.
What are the rules of how a circuit works?
To do this, it needs to flow along something, usually a copper wire, and do some work in the process, like turn on a light or spin a motor. At the end of the day, all electricity wants to find its equilibrium at ground (0v). The only way to do this in a battery is to move from the positive to the negative side.
Why does power flow from one area to another?
Regardless of where this power flows from, its purpose is always the same – to get from one area to another, and in the process to do some work, like charging your computer or turning on your lights. The fundamental component of this flow of power is that electricity will always want to flow from a higher voltage to a lower voltage.
Why does electricity have to flow in a circuit?
The only reason to make electricity flow is to give it some work to do. This process of electricity doing work in a circuit is called load. Without having a load, or some work for electricity to do, then there is no point in having a circuit.
What happens if you connect a battery to the ground?
If you connect only the high potential side of the battery to the ground, it will not noticeably change the process. Unless you have a circuit, current does not flow. There will be some minor current which goes through the air to complete the circuit, but that will be very minor indeed compared to self discharge. You won’t notice the effect.