I have two different DC power supplies (6 and 12 volts, let's call them A and B). They connect to the wall and provide a negative and a positive terminal each.
I tried to measure the voltage between the positive terminal of A and the negative terminal of B and measured 0V.
I don't understand why the potential difference between the + and - terminals of different power supplies is 0V. One could say that they don't complete a circuit, but they should, they both come from the mains of my house.
Can someone please explain me what I am thinking wrongly?
Thanks in advance, Calvin