How do electric circuits work?

Flick a switch, and a globe lights up, instantly. But what's really happening inside those wires?

Every circuit needs three things. An energy source, like a battery. Wires, to carry the energy. And a load, like a globe, that turns that energy into light, and a little heat.

But they only work when they're joined in a complete loop. Electric current flows out of the battery, along the wire, through the globe, and all the way back again.

A switch lets us open and close the loop. Close the switch, and we have a closed circuit. Current flows, and the globe glows. Open the switch, and there's a gap. The current stops, and the globe goes dark.

So what can bridge a gap? Let's test some things. A metal paperclip? The globe lights up! A plastic ruler? Nothing at all.

Metals, like copper, are conductors. They let electric current flow through them easily. Plastic and rubber are insulators. They block the current. That's why wires have copper inside, wrapped in plastic, to keep us safe.

Now let's add a second globe to the same loop. Both glow a little dimmer. This is a series circuit. There's only one path for the current. So if one globe breaks, the path is broken, and the other globe goes out too.

So, a circuit needs a source, wires and a load, joined in a complete loop. Conductors let current through, and insulators block it. And in a series circuit, one break stops everything.