Ground in DC power supply, what is it for?

[moodaeng]

Hi Guys

            I am very new to electronics. I am wondering what is the Ground wire in DC power supply?
what is the different between this wire and V-   or V+ wires?  Why do we need them?


Thanks

[Half Shell]

Edit: Apparently I was mistaken about something, please read further below.

[moodaeng]

so when I want to make 5 volt current from the machine
which channel should I plug black alligator into it? V- or Ground

When I plugged the wire into V-  / Ground the output is different.


is Ground channel equal to real earth ground?

[Soeren]

Hi,

Let's not get confused here...

Groun should be 0V (NOT -V), as 0V is the reference by which the amplitude of the positive or negative voltage is measured and ground should be neutral (again with respect to 0V => ground = 0V).

Some people might label ground as -V, but that's very wrong - please don't spread this wrong behaviour, standards shouldn't be "watered down".

On a battery (or cell) there is either 0V and +V, OR 0V and -V (this latter constellation is called positive ground).