Voltage and current

Hmmm. - You got a spare battery? - Here! Hey, how is it a battery actually makes a lamp light up? Huh? Haven't you heard the story about the children in the lighthouse? Mmm.

Don't think so. Once upon a time, a long time ago, there was an island in a stormy bay. On the island was a lighthouse, and in the lighthouse, lived thousands of children... ... the children were so unhappy, as they were sick of of being cramped together in the old tower... The children yearned for the mainland, where there was plenty of room, and everything a child could wish for.

Never had the children longed so much for the mainland. Then one day, the good fairy Ampera came, and built a bridge, between the island and the mainland. The children rushed out on the bridge, to get to the mainland, as fast as they could. Soon, it was both crowded and hot on the bridge, from all the children running. But hang on.

What's this got to do with the flashlight? Yes, what has this to do with the flashlight? Well, look at the battery. It's full of electrons, over here, at the negative terminal. The electrons are crowded, and don't like each other at all.. ...

so they yearn for the positive terminal, where there's room to spread out. Just like the lighthouse, on the island! The lighthouse, crowded with children, is just like the negative terminal on the battery. And the mainland, where there's plenty of room, is just like the positive terminal of the battery. The electrons, just like the children, are yearning to get from one side to the other!

But when it's electrons doing the yearning, we call it voltage. Then came the good fairy and built a bridge. Then the children's yearning could cause movement, as the children run across the bridge. Same thing when you turn on the flash light. Then the electrons rush through the thin wire, inside the lamp.

The number of electrons that rush through the wire every second, is what we call electric current. The more electrons, the higher the current, and the more brightly the lamp lights up! Voltage and current are different things. There can be voltage in the battery and still no current running through the lamp. In the same way, the children can long for the mainland, even if there's no bridge to run across.

It's only when you flick the switch on the flashlight, that the voltage causes a movement of electrons through the filament in the lamp. Voltage causes current. Current causes light. What is it then that makes a battery run out, when it's been used for a while? Well, the voltage drops when enough electrons have rushed over to the other side.

But all of them haven't rushed over. They have spread out, and now it's equally crowded everywhere. Nobody is longing to get anywhere. And when the voltage drops, the current drops. The light goes out.

Without longing, no movement. Without movement, no light. Scary story, stuck on a crowded island, with no wifi. Yeah, it has a lot of potential. Wanna hear the end?