Why do circuits need a loop?

[Legion]

I found these videos do a real good job of explaining the basics.

I love these old military videos. I watched one on AC motors and it explained it so well.

[edy]

I guess another way to think about it is this.... It is like musical chairs.

Electrons don't simply move "in bulk" from one place to another. If they did, they would create a huge charge difference and what you'd be talking about is static electricity. Static can be pretty impressive but not enough energy there to power much, maybe for a split second. And the electrons would soon find the forces so great that they will want to move backwards to equalize things.

Instead, it is like the game musical chairs. A bunch of chairs are in the center and people continuously move from one chair to another, in a loop. Think of the chairs as the metal in your wire and people are the electrons moving. Music is the electromotive force causing the people to move. Stop the music and everyone sits in the chairs and the circuit is off.

So in a circuit, you NEED A LOOP because electrons are just jumping from one atom to the next in the metal conduction path. As electrons move to the next atom, they will leave a space in the previous atom that needs to be filled by an electron that also jumps, and so on. Around and around it goes. Without a loop, the electrons in the wire will have to be pushed all the way over to one side, making the entire charged positive on one end and negative on the other. The electrons wouldn't be able to move anymore and there would be nothing happening after only a split second.