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Cells in series and parallel
Intermediate
Series adds emf; parallel reduces internal resistance.
In series EMFs add (and internal resistances add): more voltage. In parallel EMF stays the same but the internal resistance falls and capacity increases.
Four 1.5 V cells in series: 6 V.
Mix only identical cells in parallel.
In more detail
Cells in series add their EMFs and share the same current, while cells in parallel share the same EMF and supply more current. Internal resistances combine in a similar way.
Real-world uses
- Torches use cells in series to increase voltage.
- Battery banks use parallel cells to supply more current.
- Electric cars connect battery cells in series to get high voltage, and in parallel to increase the total capacity.
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Frequently asked questions
Why connect cells in parallel?
To increase the current capacity and extend battery life.
Can mismatched cells be mixed?
It is not recommended, as the weaker cells can drain or get damaged.
How do cells in parallel affect internal resistance?
Parallel cells share the current, so the combined internal resistance is lower than for a single cell.
Related topics in Current Electricity & Circuits
Heating effect of current · Electrical energy and cost · EMF and internal resistance · Kirchhoff's current law · Kirchhoff's voltage law · Wheatstone bridge