# Positive, negative & GND problem

#### 1:1

Joined Jan 25, 2007
27
Hai forum member,

If said my original circuit was 5volt to GND but i connected to +5volt to -5volt, what will be happen??

How to distinguish and when to assign positive,negative & GND to the circuit?

Thanks

#### beenthere

Joined Apr 20, 2004
15,819
Hi,

I do not understand your first question, except that a connection to a wrong polarity voltage will almost certainly cause semiconductors in the circuit to fail.

If you have two voltages present in a circuit, and know what they should be, then you can check for the difference voltage between them. Going from +5 to -5 will measure 10 volts. It will be +10 if your negative lead is on the negative voltage. You can find common by measuring from one on the known voltage points to one that lets the meter measure both +5 and -5 when the neagtive lead stays there, and the other moves from the +5 pont to the -5 point.

#### 1:1

Joined Jan 25, 2007
27
Thank beenthere,

Let's describe clearly for my first question.
If i was connect at one end with +5volt and the other end was connected to GND, this circuit will said it operated at 5 volts.
But if i replace the GND to -5volts, is this mean the total operate voltage in this circuit is 10volt.

i was confusing with, if i supply +12volt to the motor and grounded it, what is the different between supply +12volt and replace the GND by -12volts.

#### beenthere

Joined Apr 20, 2004
15,819
Then the motor will have 24 volts across it.

#### thingmaker3

Joined May 16, 2005
5,083
Note that when we double the voltage across any given fixed impedence, we double the current through that impedence. This quadrouples the power which must be dissipated as heat or some other energy. If the components are unable utilise or dissipate this extra power, they will be damaged by the extra heat.