Can I use 12 V and -12 V together?

Question

I am sorry if this question is pretty easy but I am a beginner.

I have a PC PSU that provides two lines:

12 V 11A
-12 V 1.5A

If I used them together will I get 24V, and how many amps can they provide?

Answer 1

Can I use 12 V and -12 V together?

Yes

If I used them together will I get 24V

Yes, if you treat what is originally labeled as -12 V as "ground", and treat what was originally labeled as "ground" or "0 V" as +12 V. Then, what was originally labeled as +12 V, will be +24 V (with respect to your new ground).

how many amps can they provide?

Unfortunately, for a 24V circuit, only the 1.5 A that your new ground (the former -12 V) will accept.

[You could have some circuitry which is referenced not to ground, but to your new 12 V terminal, but interfacing it with a 24 V circuit referenced to your new ground would require special care. The two circuits might communicate via opto-isolators, or signal transformers, or some other mechanism. With care, you could have part of your circuit still running on 12 V and 9.5 A or more (depending on how much current is used by the 24 V circuit).]