Electrical Circuits
Current Divider
A current divider splits a total current between parallel branches. The current through one branch of a two-branch divider is the total current multiplied by the other resistance divided by the sum. Note the inversion: the smaller resistance carries the larger current, because each branch has the same voltage across it. The two-branch formula does not apply unchanged to three or more branches.
Current Divider
I1 = I_total × R2 ÷ (R1 + R2)
Variables and units
| Symbol | Quantity | Unit |
|---|---|---|
| I1 | Current through branch 1 | A |
| I_total | Total current entering the parallel pair | A |
| R1 | Resistance of branch 1 | Ω |
| R2 | Resistance of branch 2 | Ω |
Conditions of application
Exactly two parallel branches. For three or more branches, use conductances or reduce the network in steps. The branches must share the same two nodes.
Worked example
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Split a total current between two parallel resistors.