Current in parallel circuits
The current flowing in a parallel circuit can be investigated by connecting the circuit below.
Once more, put one ammeter in position A1 and record the reading in a suitable table.
Then move the ammeter to position A2, A3 and then to A4.
Results
A1 = 3.2A.
A2 = 1.6A.
A3 = 1.6A.
A4 = 3.2A.
Conclusion
- The current in a parallel circuit splits up between the branches of the circuit and then combines again before it goes back into the battery.
- The current in each branch adds up to equal the current flowing through the battery.
- More current is flowing than for two bulbs in series with two cells – the cells will run down more quickly.
In the diagram, 6 A flows through the cell.
The circuit has three branches, each with an identical lamp, so 2 A flows through each one.
Question
Look at the parallel circuit below, where the lamps are identical - what is the reading at each position?
Position 1
Position 2
Position 3
Position 4
Position 1 = 0.2A
Position 2 = 0.1A
Position 3 = 0.2A
Position 4 = 0.1A
Look carefully where the current splits.
Before the split you get full current.
The current in each branch is less than the full current but then joins back together and adds up to the full current again.
