Current division can be applied when two resistors are in parallel. This is because both resistors are receiving the same voltage, and since the source current is the same, the current through each branch must be related to the value of the resistances.
| I1=I*R2/(R1+R2) | I2=I*R1/(R1+R2) |
| because... | because... |
| V1 = IR1 | V2 = IR2 |
| I = Vs/(R1||R2) | I = Vs/(R1||R2) |
| R1||R2 = R1R2/(R1+R2) | R1||R2 = R1R2/(R1+R2) |
| I1 = Vs/R1 | I2 = Vs/R2 |
| Vs = I (R1R2/(R1+R2) | Vs = I (R1R2/(R1+R2) |
| I1=I*R2/(R1+R2) | I2=I*R1/(R1+R2) |