What's the fuss about electrical circuits?

Thinking about circuits with loops

Connect a battery a bulb in a complete circuit, and the bulb lights up. That's what you do in school, and it looks something like this.

There is one loop, made of four things.

In a torch, working a switch links the battery to the bulb.

The wires that link battery to bulb can be long — from an articulated truck battery to the rear lights. The loop can be even longer for mains electric circuits in houses. A power station and the bulb in the hime are in the loop. Power stations can be tens or hundreds of miles from the home. But there is always a loop.

Here you'll find out a good way to think about what's going on in these circuits. From these few examples, you can tell that something needs to do the job of the battery, getting run down, linked to whatever is doing the lighting, heating, or another job for us.

Drawing keeps things simple

Pictures are one way of showing what the world is like, but careful drawings can help us re-imagine it. Learn to draw electrical circuits, and it'll make reasoning about them more reliable.

What's important here is that there is one wire from each end of the battery to each end of the bulb. How things are connected is essential, not the length of the wire or how the wires bend.

The stuff that goes around wires does not see bends as we do

You need a loop

Complete the loop, and the bulb lights right away. Break the loop anywhere, and the bulb goes out.

Next, you'll learn a helpful way to think about what's going on.