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Useful circuits

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It is important that you know about current and voltage in series and parallel circuits. This revision bite will take you through series and parallel circuits, current in series circuits, current in parallel circuits, voltage across components in a series circuit, voltage across components in a parallel circuit and resistors in series and parallel circuits.

Work through them all or go to the ones that interest you. You may wish to print a hard copy for your reference.

# Series and parallel circuits

You should be able to recognise series and parallel circuits.

In a series circuit there is only one path for the current and the current is the same at all points. Here is an example of such a circuit.

In a parallel circuit there is more than one path for the current to follow. At some points in a parallel circuit there will be junctions of conductors. Junctions are shown by dots on circuit diagrams. The sum of currents in parallel branches is equal to the current drawn from the supply. This circuit shows two lamps in parallel.

Some parallel circuits have switches in parallel, as the circuit shown here.

## Try this question

Question

Which circuit shows:

• resistors in series?
• resistors in parallel?
• switches in series?
• switches in parallel?