# Measuring current

We can measure the amount of electric currentElectric current is a flow of electric charges (electrons). flowing in a circuitA collection of wires and electric components connected together in such a way that electric current can flow through them. with a device called an ammeter. The unit of electric current is the AmpThe Amp is a measure of electric current. - which is often abbreviated to the letter A, especially if it comes after a number. So, for example, 3 Amps can also be written 3A.

To measure the current flowing in a circuit you must connect the ammeter in series with the other components. In a circuit diagram we represent an ammeter like this: • Use Circuit Builder to measure the amount of electric current entering and leaving a bulb in a series circuit

Try it out and you'll find that the current in a series circuit is the same no matter where you put the ammeter.

It doesn't get 'used up' as it flows through the components - which is what lots of people think.

What actually happens is, the energy is transferred to the components in the circuit by the electric current which is made up of electric charges. In this case, there is one component, the bulb. The bulb then transfers the energy to the surroundings by heat and light.

Now use Circuit Builder to investigate the electric current flowing in different parts of a parallel circuit.

The current in the branches of a parallel circuit add up to the current flowing in and out of the cell or battery.

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