Parallel Resistance Calculator
Calculate equivalent resistance when resistors are connected in parallel
Understanding Parallel Resistance
What is Parallel Connection?
When resistors are connected in parallel, they are connected across the same two points, creating multiple paths for current to flow. The voltage across all resistors is the same, but current divides among them.
Formula
For parallel resistors, use the reciprocal formula:
1/Rtotal = 1/R1 + 1/R2 + 1/R3 + ... + 1/Rn
For two resistors, there's a simpler formula:
Rtotal = (R1 × R2) / (R1 + R2)
Why Resistance Decreases
In parallel circuits, total resistance always decreases because you're creating additional paths for current to flow. Think of it like adding more lanes to a highway - more paths mean less resistance to traffic flow.
Where Parallel Circuits Are Used
- House wiring - all outlets are in parallel
- Battery configurations for higher current
- Load balancing in circuits
- Creating specific resistance values
Example Calculation
Two resistors: 100Ω and 200Ω in parallel:
Rtotal = (100 × 200) / (100 + 200) = 20000 / 300 = 66.67Ω
Notice the result is less than the smallest resistor!
Key Points
- Total resistance always decreases in parallel
- Result is always less than the smallest resistor
- Voltage is the same across all resistors
- Current divides among the paths
- If one component fails, others still work