Electrical Circuit
Electricity and Magnetism

Describing parallel circuits

Teaching Guidance for 11-14 Supporting Physics Teaching

Just where do the charged particles come from?

In describing what happens when a second bulb is added in parallel, it is quite common for teachers to use phrases such as:

Teacher: When the second bulb is added in parallel, twice the current is drawn from the battery.

Such expressions are potentially misleading in that they paint a picture of the battery providing the additional current. Instead, it is the additional charged particles from the second loop which flow through the battery.

It would be better simply to say:

Teacher Tip: When the second bulb is added in parallel, there is twice the current in the battery.

Different ways of drawing the same circuit

Teacher Tip: Try exploring (with pupils) other representations for parallel circuits, showing that the same circuit can be drawn with different, but equivalent, layouts.

Remember – it's only what's in the loop that's important. The whole loop functions as an integrated system: we'd suggest not trying to explain it as stories about isolated actors (journeys undertaken by one charge, the current splitting, etc.).

Only in the very simplest cases are circuits either series or parallel. For more precision, you might refer to series connections or parallel connections. Later on, pupils may well meet circuits where things are connected in both series and parallel in the same circuit. But for very simple circuits you can use the terms series circuits and parallel circuits without causing too much confusion.

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