Electronics makes no sense

Help me, /sci/!

How come complete circuits are required for electric current to flow?

So the electrons can go somewhere. loll you can't just put them in a big pile

UNLESS

you have a capacitor :O

because god, when he created the universe, thought it would be helpful to have electricity run in circuits.  he's always thinking of us, you know.

>>2
So let's say we connect the positive terminal of one battery to the negative terminal of another. Does current flow?

Lets make BIG capacitor to capture A LOT of electrons!

>>5
I don't get it. That's like saying: let's make a BIG box to hold A LOT of STUFF. So what?

>>6
What's your point?

>>7
My poin is that >>5 has no point.

>>8
No it's not. Your point is that you're racist against capacitors and big boxes.

>>9
No it's not. My POINT is THAT >>1.

>>10
Racist.

>>11
What's wrong with that? You racismist.

Surely someone in /sci/ must be enough of not an idiot to know why circuits work and things that aren't don't.

Analogy time!

Battery = parking garage
electrons = cars
wires = roadway

The cars (electrons) come out of the parking garage exit (- terminal), enter the roadway (wires), and start driving (current).
If there's a break in the roadway, the cars can't drive, unless there's a flat (conductive) surface to go to. Also, the parking garage won't let a car out unless another one comes back, thereby creating the necessity for a closed circuit.

More applicable items:
Road width = resistance
# of cars passing per second = amperage
speed of cars = voltage
Gas tank level = battery life

>>13
Now apply your analogy to explain the workings of capacitors while the rest of us think about the question at hand.

Electrons move only if there is an electronic field. This electronic field is produced only if there is some positive charge at one end and some negative charge at the other end. This only works when the positive and negative charges are connected.

dont think of it as a "complete" circuit. just think of it as needing some sort of reference ground so that a potential difference exists across your load..

probably left out too much

>>15
I thought moving electrons were what created the electronic field.

>>1
because that's how god decided it should work 6,000 years ago when he created the universe in only six days.

>>6
Then we break it and see what happens. Maybe division by zero or something.

>>17
Nope. Moving electrons don't cause any field. The emf does.

How capacitors work:
http://www.amasci.com/emotor/cap1.html

>>15
>>17
>>20
Moving CHARGE causes an electric field.  The emf (or electro motive force) is the effect that field has on charges.  For instance (and you can try this at home) if you get an ammeter and attach it to a hoop of conductive material (such as iron) and pass a magnet through it current will flow.  Which direction you pass the magnet through determines the direction of the current.

Capacitors work by seperating two conductors by a dialectric.  This is usually an insulator of some kind (can be air).  If you keep this attached to a power source the electrons will eventually move away from one side, and be piling up on the other side, creating a net difference in potential between the two sides (voltage).  When this gap is bridged the capacitor is discharged.

Charge needs to move to create an electric field?

I thought you could just have point charges.  Liek in phsyics 102 questions

Of course I'm in biochem so I wouldn't really know

>>23
Yeah, you're right.  Moving charge creates a magnetic field, which is related, but not the same.

Anything with charge creates an electric field.  

Y lazer has to be charged?

>>25
Your garden-variety household electrical outlet doesn't provide enough continuous electricity (once converted to DC) to power your average whoop-shooping lazer.  Therefore, the electricities has to be charged up (like in a capacitor) in order to fire a lazer with adequate power to shoop da whoop.
Think of how a toilet works. The water has to be stored in the tank in order to have enough to flush.

>>12

Conservation of charge.  Related to that is Kirchoff's Current Law and Kirchoff's Voltage law.

Basically you can't destroy or create electrons any more than you can destroy or create any other type of matter (under normal operating conditions).  And its really hard to store an electric charge under the quantities and conditions you want to make it useful, and much easier to change work into electrical power.  Think of a basic circuit with a voltage supply and a resistor.  Then think of an analog equivalent: a water pump connected to a pipe with a waterwheel in the middle thats connected to the other end of the pipe.  If you open up the "pipe" then the pump runs out of water really fast.  But while the pipe might last a couple seconds, circuits scale down much more (atoms are smaaaalllll) and it would be milliseconds, if that.

>>27
That's right, if the electrons somehow were to keep moving, then the ones at the end would have to move out of the wire and into the air or something. That's not possible.

>>28
Well, it is possible, but you need a fuckton of electrons and you end up with ionized air.

Think of it like a hose filled with water:

the only way you can get water flowing is if you have a constant stream of water leaving the hose as it is coming in.

>>30
how about refining it: the hose must be connected to a tank on both ends.

>>31
That's right, because unlike water, electrons have to move through resistance, which is usually greater in air rather than in most conductors, which is different from water.

induction circuits can be deemed technically open but still electromagnetically closed

because not all elements in this universe are conductors. Duh.