In this topic we are learning to: z Distinguish between the wiring of components in series and parallel circuits.
z Compare voltages and currents in series and parallel circuits. There are two ways of connecting components in electric circuits:
z When components are connected in a single loop with each other and the battery, they are connected in series.
z When components are connected in different branches, they are connected in parallel.
These bulb are connec in parallel
Fig. 18.7.1 A series circuit
These bulbs are both connected in series Series and parallel
Read the following statements and discuss with your partner whether the lights involved are wired in series or parallel:
1. When a single bulb breaks on a set of Christmas tree lights, all the lights go out.
2. One of the bulbs in the headlights of a car breaks but the other stays on.
3. A televison, cooker and washing machine can be operated independent of each other.
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In the series circuit in Fig. 18.7.1, if one bulb blows then the other goes out too. This is because they are connected in a single loop with each other. If one of the bulbs blows in the parallel circuit in Fig. 18.7.2, the other can stay on as it is still connected in a complete circuit to the battery.
z Ammeters measure the current flowing through a circuit, so they have to be connected in series with components.
z Voltmeters measure the potential difference across a component. This means they must be connected across a component in parallel to measure the difference in energy between one side and the other.
