 When dealing with circuits, we also need a way to measure the current through a wire. So the way we do this is using an ammeter. So an ammeter is simply a device which measures the electrical current passing through it. So here I have a multimeter which I can set to work as an ammeter. So here I have a circuit. I can connect it like this. This is causing the light bulbs to shine and I would like to measure the current through it. So in order to do this, I'm going to need to use my ammeter. So what I do is I actually need to disconnect the circuit. Then I'm going to connect one end of my ammeter to the light bulb and the other end to the battery. And now when I connect this terminal to the battery, current is flowing through the ammeter, then through the light bulb, through the other light bulb to the other terminal of the battery. So the ammeter itself has become a part of the circuit. And we can see that the ammeter is measuring here. I've set it to milliamps. So 14.4 milliamps of current is going through the circuit. So here is a diagram of the circuit. And so the way I would represent an ammeter is with this symbol here. So it's an A inside a circle. But in order to get to measure the current that's flowing through a wire, what I would have to do is disconnect that wire and then put the ammeter into that part of the circuit. So now the ammeter is actually part of my circuit. So current will move through the circuit, flowing through both light bulbs and through this wire here. And the ammeter measures the amount of current going through this point in the circuit.