Ok, I know the basics (volts, amps, various components, electrons flow out of -ve)

I started having a go at a little electronic sim, it's very simple right now with quite a few flaws like current doesn't split, it doesn't use relistic values but any way,

How in real life do the components only work when they are in a complete dircuit? I've found that programming things the way they do in real life usually works best.

(Oh, and here's my shoddy swf: http://ed.gamegeared.com/flash/circuit.swf )