Voltage question

BigD

Joined Oct 9, 2006
1
So I know a voltage can be negative with respect to another relatively higher voltage, but can a voltage ever be lower than or negative with respect to earth ground (0 volts).

pebe

Joined Oct 11, 2004
626
So I know a voltage can be negative with respect to another relatively higher voltage, but can a voltage ever be lower than or negative with respect to earth ground (0 volts).
Yes it can. A simple example would be where you connect the +ve pole of an AA cell to ground. Its -ve connection will then be at a potential of -1.5V relative to ground.

jtodd5781

Joined Sep 29, 2006
6
Yes it can be negative in respect to ground.

Papabravo

Joined Feb 24, 2006
18,400
An AC signal is both positive and negative with respect to ground.

Joined Jan 10, 2006
614
And a Split Rail supply (common in Amplifiers and also PC supplies) has both Positive AND Negative rails with respect to ground.

thingmaker3

Joined May 16, 2005
5,083
Here's another way of looking at it: "Negative" and "positive" simply indicate whether current would flow to the reference or from the reference as a result of the potential.