# Trying to Understand electricity

#### caper

Joined Jul 8, 2006
2
Why a static charge neutralizes when touched by someone but if you touch only the negative side of battery
Nothing happens. Would the Negative side of a battery be similar be similar to an object negatively charged?

#### beenthere

Joined Apr 20, 2004
15,819
Hi,

You don't pick up a charge when you touch a battery terminal unless the other terminal is connected in such a way that you become part of an electrical circuit. Otherwise, the battery voltage has a potential only with the other battery terminal. and touching one or the other does not increase/decrease your body's charge with respect to ground, or any other reference point.

Voltages are measured relative to some point. Usually it is ground, quite literally the potential of the earth beneath your feet. All AC voltages are so measured. If the circuit happens to be self-contained, then ground becomes "circuit ground", and voltages are measured relative to that point.

Thechnically, the static charge is not neutralized by the touch. The voltage potential between onjects is simply equalized. Static voltages can produce huge currents - lightning - but rely on non-conductive surfaces to accumulate. It's not really an apples/oranges situation, but static electricity just does not work in quite the same way as, say, electricity from a battery.

#### caper

Joined Jul 8, 2006
2
Sorry still confused.
Why don't current flow if you connect a wire from the Negative terminal of one battery to the positive terminal of a different battery.
That would be a difference in potential

#### JoeJester

Joined Apr 26, 2005
4,390
For current to flow you need a complete circuit.

Connecting one wire between the negative terminal and a positive terminal is nothing until you complete the circuit.

How long will a battery last in a device with the device turned off [circuit not complete] vice how long it lasts when the device is turned on [circuit complete]. There is a considerable difference between the two lifespans.

The positive or negative potentials exist depends on where you place the meter common.

#### rukrazy?

Joined Mar 5, 2005
21
Also two batteries have thier potential independent from the other source.
If there is a static charge difference then it would balance using the wire between the two objects. But it would not change the internal voltage of either.

#### Codesmith

Joined Jul 19, 2006
5
In college I asked my physics professor this same question.

My understanding is that in order to sustain the chemical reaction which produces the voltage equal the current leaving one end of the battery needs to equal the current entering the other.

Otherwise the reaction stops and so does the voltage.

The same doesn't hold true if for example you take the powersupply from a PC and short the green wire to black to start it up.

You can get a complete the circuit with any grounded wire, just like AC.