Basic electric circuits concept help required

goomer

I'm reading a tutorial about the basics of circuits and I don't understand this concept. In the three last circuit diagrams in the link located below, there is a break in each of the circuits. The ends of the breaking points are labeled + and -, but how can that be?

My thoughts:

If there is no electrical flow if there is a break in the circuit, shouldn't that mean that the wires should all be neutral?

Or, seeing as only electrons are flowing through the circuit, shouldn't both ends of the break be negative?

http://www.allaboutcircuits.com/vol_1/chpt_1/4.html

berkeman

A break in the circuit keeps current from flowing. But there can still be a voltage across the break. Think of a battery just sitting on the table in front of you. There is no external connection between the + and - ends, so no current flows. But there is still a voltage between the + and - ends, right?

goomer

I see...so when the circuit is broken, you can think of the two individual sections of wires as extensions of the battery?

Also, is there no flow because nothing is going through the wire at all, or is it because there is an electron build up in the wire?

berkeman

[QUOTE=goomer;3991003]I see...so when the circuit is broken, you can think of the two individual sections of wires as extensions of the battery? [quote]
Exactly

When you initially connect the open wires to the battery, there is a very small current that flows to "charge up" the parasitic capacitance of the wires. Once the wires are charged to the battery voltage, no more current flows if the circuit is kept open/broken.

CWatters

If you like the water analogy then a broken wire is like a pipe that has been cut and the ends sealed. There is pressure (voltage) at the ends of the pipe but no flow (current).

goomer

Got it, thanks guys :)