Resistors in Parallel
Resistors in Parallel
Resistors in parallel share the same voltage and provide extra current paths, so the combined resistance is always less than the smallest one.
For two resistors R_eq = R_1·R_2/(R_1 + R_2). where R_1 and R_2 are the parallel resistances.
Inputs
R_1 := 100 Ohm=100 Ω
R_2 := 150 Ohm=150 Ω
The product-over-sum rule for two parallel resistors.
R_eq := R_1·R_2/(R_1 + R_2)=60 Ω
Results
The result is smaller than either resistor because the extra path lets more current flow for the same voltage. Equal resistors give exactly half.
Assumptions & limitations
- Ideal resistors.
- Common voltage across both.
- Wiring resistance neglected.